Explanation:
Friction acts between two surfaces in contact only and opposes the movement of one body with respect to another. Therefore friction is a force which opposes the relative motion between two bodies. If a body is moving it is slowed down by frictional force applied on it by the surface on which it is moving.
Heather and Jerry are standing on a bridge 46 m
above a river. Heather throws a rock straight down with a speed of 14 m/s
. Jerry, at exactly the same instant of time, throws a rock straight up with the same speed. Ignore air resistance. How much time elapses between the first splash and the second splash?
The time elapsed between the first splash and the second splash is approximately 0.69 seconds.
To calculate this, we consider the motion of two rocks thrown simultaneously from a bridge. Heather throws a rock straight down with a speed of 14 m/s, while Jerry throws a rock straight up with the same speed.
We use the equation for displacement in uniformly accelerated motion: s = ut + (1/2)at^2.
For Heather's rock, which is thrown downwards, the initial velocity (u) is positive and the acceleration (a) due to gravity is negative (-9.8 m/s^2). The displacement (s) is the height of the bridge (46 m).
Solving the equation, we find two possible values for the time (t): t ≈ -4.91 s and t ≈ 1.91 s.
Since time cannot be negative in this context, we discard the negative value and consider t ≈ 1.91 s as the time it takes for Heather's rock to hit the water.
For Jerry's rock, thrown upwards, we use the same equation with the same initial velocity and acceleration. The displacement is also the height of the bridge, but negative.
Solving the equation, we find t ≈ -5.68 s and t ≈ 1.22 s. Again, we discard the negative value and consider t ≈ 1.22 s as the time it takes for Jerry's rock to reach its maximum height before falling back down.
To find the time difference between the first and second splash, we subtract t ≈ 1.91 s (Heather's rock) from t ≈ 1.22 s (Jerry's rock). This gives us a time difference of approximately 0.69 seconds.
Therefore, the time elapsed between the first splash and the second splash is approximately 0.69 seconds.
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4. Calculate the displacement that would be needed to get the ball into the hole on the first stroke if a golfer takes three strokes to get his ball into the hole once he is on the green. Given that the first stroke displaces the ball 6 m north, the second stroke 3.0 m southeast, and the third stroke 2.0 m southwest. (2.56 m at 1.61° E of N)
The displacement needed to get the ball into the hole on the first stroke is approximately 9.8731 m at an angle of 12.01° east of north
To calculate the displacement needed to get the ball into the hole on the first stroke, we need to consider the vector components of each stroke and combine them to find the resultant displacement.
First, we break down the second stroke of 3.0 m southeast into its north and east components. Since it's at a 45° angle, both components will have the same magnitude of 3.0 m.
North component = 3.0 m * cos(45°) = 3.0 m * 0.7071 ≈ 2.1213 m
East component = 3.0 m * sin(45°) = 3.0 m * 0.7071 ≈ 2.1213 m
Next, we break down the third stroke of 2.0 m southwest into its north and west components. Since it's at a 45° angle, both components will have the same magnitude of 2.0 m.
North component = 2.0 m * cos(45°) = 2.0 m * 0.7071 ≈ 1.4142 m
West component = 2.0 m * sin(45°) = 2.0 m * 0.7071 ≈ 1.4142 m
Now, we can sum up the north and east components from the first, second, and third strokes:
North displacement = 6.0 m + 2.1213 m + 1.4142 m = 9.5355 m
East displacement = 0 m + 2.1213 m - 0 m = 2.1213 m
Finally, we can calculate the magnitude and direction of the resultant displacement using the Pythagorean theorem and trigonometry:
Resultant displacement = √(North displacement^2 + East displacement^2) ≈ √(9.5355 m^2 + 2.1213 m^2) ≈ 9.8731 m
The direction can be found using the tangent function:
Direction = arctan(East displacement / North displacement) ≈ arctan(2.1213 m / 9.5355 m) ≈ 12.01°
Therefore, the displacement needed to get the ball into the hole on the first stroke is approximately 9.8731 m at an angle of 12.01° east of north.
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A platinum resistance thermometer has resistances of 210.0 Ω when placed in a 0°C ice bath and 237.8 Ω when immersed in a crucible containing a melting substance. What is the melting point of this substance? (Hint: First determine the resistance of the platinum resistance thermometer at room temperature, 20.0°C.)
The resistance of a platinum resistance thermometer is 200 Ω at 0°C and 255.8 Ω at the melting point. Using the resistance-temperature relationship and calculations, the estimated melting point is approximately 19.93°C.
The resistance of a platinum resistance thermometer is 200 Ω when placed in a 0°C ice bath and 255.8 Ω when immersed in a crucible containing a melting substance. To determine the melting point of the substance, we need to calculate the temperature at which the resistance reaches 255.8 Ω.
First, we find the temperature coefficient of resistance (α) using the formula α = (R - R₀) / (R₀ * T), where R is the resistance at the melting point, R₀ is the resistance at 0°C, and T is the temperature at the melting point.
Substituting the given values, we have α = (255.8 - 200) / (200 * T₀), where T₀ is the known room temperature of 20°C.
Calculating α, we find α ≈ 0.014.
Next, we use the resistance-temperature relationship equation R = R₀(1 + αT) to solve for the melting point temperature (T). Substituting the known values, we have 255.8 = 200(1 + 0.014 * T).
Simplifying the equation, we find 1.279 = 1 + 0.014T.
Solving for T, we get T ≈ 19.93°C.
Therefore, based on the given data, the estimated melting point of the substance is approximately 19.93°C.
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A graph titled energy versus velocity is shown with energy on the vertical axis and velocity on the horizontal axis. The graph is a curved line opened up from bottom left to top right.
Which of the following best describes the relationship between the two variables?
A. Velocity is inversely related to energy.
B. Energy is inversely related to the square of velocity.
C. Velocity is directly related to energy.
D. Energy is directly related to the square of velocity.
The graph shows a curved line indicating that as velocity increases, energy also increases, supporting the statement that velocity is directly related to energy. Option C is correct.
The relationship between energy and velocity can be determined by examining the shape of the graph. In this case, the graph shows a curved line opening up from the bottom left to the top right. This indicates that as velocity increases, energy also increases. Therefore, the correct answer is option C: Velocity is directly related to energy. The graph does not show an inverse relationship, as energy does not decrease as velocity increases. Additionally, the graph does not follow a square relationship, as energy does not change in proportion to the square of velocity. Instead, it shows a linear relationship between velocity and energy. This means that as velocity increases, energy increases in a proportional manner. Therefore, option C is the most accurate description of the relationship between the two variables.For more questions on velocity
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during the current year, sue shells incorporated total liabilities decreased by $25,600 and stockholder equity increased by $4,700. by what amount and in what direction did sue's total assets change during the same time period?
Answer:
$20,900 decrease.
Explanation:
During the current year, Sue Shells, Inc.'s total liabilities decreased by $25,600 and stockholders' equity increased by $4,700. By what amount and in what direction did Sue's total assets change during the same time period? $20,900 decrease.
South American primates have prehensile tails, meaning their tails can grab. African and Asian primates do not have prehensile tails. This is an example of ________________.
A. geographic speciation
B. selective pressures
C. divergent boundaries
D. plate tectonics
Answer:
B. Selective Pressures
Uphill escape ramps are sometimes provided to the side of steep downhill highways for trucks with overheated brakes For a simple 18 degree upward ramp, what minimum length would be needed for a runway truck traveling 120km/h?
The minimum length needed for a runway truck traveling at 120 km/h on a simple 18-degree upward ramp is approximately 276 meters.
To calculate the minimum length needed for the runaway truck on a 18-degree upward ramp, we need to consider the forces acting on the truck and use the principles of physics.
Convert the speed of the truck from km/h to m/s:
Speed in m/s = (120 km/h) * (1000 m/km) / (3600 s/h) = 33.33 m/s.
Determine the acceleration of the truck on the upward ramp. Since the truck is traveling uphill, the gravitational force will oppose the motion of the truck. The component of the gravitational force acting in the direction of motion can be calculated as:
F_gravity = m * g * sin(theta),
where m is the mass of the truck and theta is the angle of the ramp (18 degrees). The acceleration is given by:
a = F_gravity / m = g * sin(theta),
where g is the acceleration due to gravity (approximately 9.8 m/s^2).
Calculate the minimum length needed using the equation of motion:
d = (v^2 - u^2) / (2 * a),
where v is the final velocity (0 m/s), u is the initial velocity (33.33 m/s), and a is the acceleration. Substituting the values:
d = (0^2 - 33.33^2) / (2 * (-g * sin(theta))).
Convert the angle from degrees to radians:
theta_radians = theta * (pi / 180).
Substitute the values and calculate the minimum length:
d = (0 - 33.33^2) / (2 * (-9.8 * sin(theta_radians))).
Plugging in the values, we find:
d ≈ 276 meters.
Therefore, the minimum length needed for the runway truck traveling at 120 km/h on a simple 18-degree upward ramp is approximately 276 meters.
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QUESTION 3 (a) State the difference between a transformer and an induction motor. (4 marks) (b) Neatly draw the power circuit of a 3-phase induction motor. (c) (4 marks) The methods to be employed in starting a three phase induction motor depenc upon the size of the motor and the type of the motor. State four (4) methods th can be emploved to start an induction motor (8 marks) (b) Outline the difference between a squirrel cage motor and a wound rotor motor. (4 marks)
(a) The difference between a transformer and an induction motor are:
A transformer is a device that changes the voltage of electricity, while an induction motor is a type of motor that uses magnets to create motion.Transformers are used to modify voltage levels, while induction motors are used to generate spinning motion.(c) Four methods to start a three-phase induction motor are:
Direct-on-line (DOL) startingStar-delta startingAutotransformer startingSoft-start starting(d) Difference between a squirrel cage motor and a wound rotor motor:
Squirrel cage motor are: Simple, rugged, minimal maintenance while Wound rotor motor are : Adjustable speed, high starting torque.What is the the difference between a transformer and an inductionTransformers use the power of electrical currents passing through coils to create a connection between the primary and secondary windings. Induction motors, on the other hand, use electromagnetic power to create a rotating magnetic force.
Note that a squirrel cage motor has a rotor made up of conductive bars that are shorted at both ends. The wound rotor motor has a part inside called the rotor that has three sets of wires connected to either outside resistors or slip rings.
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An earthquake caused by the movement of continents and tectonic plates wipes out half of a population of deer. All of the deer with the gene for thick fur are killed. The new population born from the survivors cannot tolerate cold temperatures causing them to migrate south. The earthquake is an example of a(n) _____________ in this situation.
A. selective pressure
B. tectonic pressure
C. geographic speciation event
D. destructive boundary
why aeroplanes cannot travel in space
Answer:
- They need oxygen to burn fuel
- Aerodynamics
- Extreme temperatures
- Radiation
- Pressure issues
Explanation:
A airplane is a heavier-than-air aircraft kept aloft by the upward thrust exerted by the passing air on its fixed wings and driven by propellers, jet propulsion, etc.
Aeroplanes cannot travel in space for several reasons:
They need oxygen to burn fuel - Aeroplane engines rely on the oxygen in the atmosphere to burn fuel and generate thrust. In space, there is no atmosphere so there is no oxygen for the engines to work.
Aerodynamics - Aeroplane wings generate lift by interacting with the air. In space, there is no air so wings would be unable to generate any lift. Aeroplanes rely on aerodynamics to fly which does not work in space.
Extreme temperatures - In space, temperatures can range from -150 degrees Celsius to 150 degrees Celsius. Aeroplanes are designed to operate within a much narrower temperature range. The extreme cold and heat of space could damage aeroplane components.
Radiation - In space, there are high levels of radiation from the Sun and cosmic rays. Aeroplane bodies are not designed to shield against this type of radiation and it could damage electronics and affect aeroplane systems.
Pressure issues - Aeroplanes are designed to withstand air pressures at altitudes up to around 12 kilometers. In low-Earth orbit and beyond, the air pressure is essentially zero. This extreme change in pressure could cause structural damage to the aeroplane.
In summary, while aeroplanes are designed to fly through the Earth's atmosphere, they lack the key features needed to operate in the extreme environment of outer space like spaceships. Aeroplanes require things like oxygen, aerodynamics and being able to withstand changes in pressure - all of which do not exist or work the same way in space.
Explanation:
The wing is pushed up by the air under it. Large planes can only fly as high as about 7.5 miles. The air is too thin above that height. It would not hold the plane up.
A shaft carries five masses A, B, C, D and E which revolve at the same radius in planes
which are equidistant from one another. The magnitude of the masses in planes A, C and
D are 50 kg, 40 kg and 80 kg respectively. The angle between A and C is 90° and that
between C and D is 135°. Determine the magnitude of the masses in planes B and E and
their positions to put the shaft in complete rotating balance.
The magnitude of the masses in planes B and E is 40 kg, and their positions are 120° and 240°, respectively, from the reference point on the shaft to achieve complete rotating balance.
To achieve complete rotating balance, the sum of the moments of the masses in planes A, C, D, B, and E should be equal to zero. Let's determine the magnitude of the masses in planes B and E and their positions.
Consider the moments of the masses in planes A, C, and D. The moment of a mass is given by the product of its magnitude and the sine of the angle between the mass and a reference line. The moments of masses A, C, and D are:
Moment of A = 50 kg * sin(0°) = 0 kg·m,
Moment of C = 40 kg * sin(90°) = 40 kg·m,
Moment of D = 80 kg * sin(135°) = -80 kg·m.
Since the moments of A, C, and D are known, we can use the principle of complete rotating balance to determine the magnitude and position of the masses in planes B and E.
Let's assume the magnitude of the masses in planes B and E as M. The moments of masses B and E can be represented as:
Moment of B = M * sin(120°) = M * √(3)/2,
Moment of E = M * sin(240°) = -M * √(3)/2.
Using the principle of complete rotating balance, the sum of the moments should be zero. Thus, we have:
Moment of A + Moment of C + Moment of D + Moment of B + Moment of E = 0.
0 + 40 kg·m + (-80 kg·m) + M * √(3)/2 + (-M * √(3)/2) = 0.
Simplifying the equation:
40 kg·m - 80 kg·m + M * √(3)/2 - M * √(3)/2 = 0,
-40 kg·m = 0.
From the equation, we can deduce that M must be equal to 40 kg to satisfy the condition of complete rotating balance.
Finally, we determine the positions of masses B and E. Since planes A, C, D, B, and E are equidistant from one another, and the angle between A and C is 90°, we divide the circle into 360°/5 = 72° sections. Thus, the positions of masses B and E are:
Position of B = 0° + 2 * 72° = 144°,
Position of E = 0° + 4 * 72° = 288°.
Therefore, the magnitude of the masses in planes B and E is 40 kg, and their positions to put the shaft in complete rotating balance are 144° and 288°, respectively, from the reference point on the shaft.
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A 0.05 kg bullet strikes a 1.3 kg box and displaces it by a height of 4.5 m. After hitting
the box, the bullet becomes embedded and remains inside the box. Find the velocity of the bullet-block system after it's hit.
(a) 6.76 m/s
(b) 5 m/s
(c) 9.39 m/s
(d) 7.67 m/s
Now use the above velocity (of the bullet-block system) to find the bullet's velocity before it hit the box.
(e) 196.76 m/s
(f) 100.07 m/s
(g) 209.39 m/s
(h) 253.53 m/s
Answer:
Explanation:
The answer is **(c) 9.39 m/s** for the velocity of the bullet-block system after it's hit, and **(g) 209.39 m/s** for the bullet's velocity before it hit the box.
The velocity of the bullet-block system after it's hit can be found using the conservation of energy. The potential energy of the box before it was hit is mgh, where m is the mass of the box, g is the acceleration due to gravity, and h is the height that the box was displaced. After the bullet hits the box, the potential energy of the box is zero, but the kinetic energy of the bullet-block system is mv^2/2, where m is the total mass of the bullet-block system and v is the velocity of the bullet-block system. Setting these two expressions equal to each other, we get:
```
mgh = mv^2/2
```
Solving for v, we get:
```
v = sqrt(2mgh)
```
In this case, we have:
* m = 0.05 kg + 1.3 kg = 1.35 kg
* g = 9.8 m/s^2
* h = 4.5 m
So, the velocity of the bullet-block system after it's hit is:
```
v = sqrt(2 * 1.35 kg * 9.8 m/s^2 * 4.5 m) = 9.39 m/s
```
The velocity of the bullet before it hit the box can be found using the conservation of momentum. The momentum of the bullet before it hit the box is mv, where m is the mass of the bullet and v is the velocity of the bullet. After the bullet hits the box, the momentum of the bullet-block system is (m + M)v, where M is the mass of the box and v is the velocity of the bullet-block system. Setting these two expressions equal to each other, we get:
```
mv = (m + M)v
```
Solving for v, we get:
```
v = mv/(m + M)
```
In this case, we have:
* m = 0.05 kg
* M = 1.3 kg
* v = 9.39 m/s
So, the velocity of the bullet before it hit the box is:
```
v = 0.05 kg * 9.39 m/s / (0.05 kg + 1.3 kg) = 209.39 m/s
```
The velocity of the bullet-block system after the collision is approximately a) 6.76 m/s, and the bullet's velocity before it hit the box is approximately e) 196.76 m/s.
To solve this problem, we can apply the principle of conservation of momentum and the principle of conservation of mechanical energy.
First, let's calculate the velocity of the bullet-block system after the collision. We can use the principle of conservation of momentum, which states that the total momentum before the collision is equal to the total momentum after the collision.
Let m1 be the mass of the bullet (0.05 kg) and m2 be the mass of the box (1.3 kg). Let v1 be the velocity of the bullet before the collision (which we need to find) and v2 be the velocity of the bullet-block system after the collision.
Using the conservation of momentum:
m1 * v1 = (m1 + m2) * v2
0.05 kg * v1 = (0.05 kg + 1.3 kg) * v2
0.05 kg * v1 = 1.35 kg * v2
Now, let's calculate the velocity of the bullet-block system (v2). Since the system goes up by a height of 4.5 m, we can use the principle of conservation of mechanical energy.
m1 * v1^2 = (m1 + m2) * v2^2 + m2 * g * h
0.05 kg * v1^2 = 1.35 kg * v2^2 + 1.3 kg * 9.8 m/s^2 * 4.5 m
Now, we can substitute the value of v2 from the momentum equation into the energy equation and solve for v1.
By solving these equations, we find that v1 is approximately 196.76 m/s.
Therefore, the bullet's velocity before it hit the box is approximately 196.76 m/s. (e) 196.76 m/s
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The _____, where fibers connect the brain's left and right hemispheres, thickens in adolescence, and this improves adolescents' ability to process information
The corpus callosum where fibers connect the brain's left and right hemispheres, thickens in adolescence, and this improves adolescents' ability to process information
The structure referred to in the statement is the corpus callosum. The corpus callosum is a broad band of nerve fibers that connects the left and right hemispheres of the brain. It plays a crucial role in facilitating communication and information exchange between the two hemispheres.
During adolescence, the corpus callosum undergoes a process called thickening, which refers to an increase in its size and structural integrity. This thickening is a result of ongoing myelination, a process where the nerve fibers are coated with a fatty substance called myelin. Myelination enhances the speed and efficiency of electrical impulses transmitted along the nerve fibers.
The thickening of the corpus callosum in adolescence has significant implications for cognitive functioning and information processing. It allows for enhanced coordination and integration of activities between the brain's hemispheres. The improved connectivity between the left and right hemispheres facilitates the transfer of information, enabling adolescents to utilize both sides of their brains more effectively.
As a result, adolescents experience improvements in various cognitive abilities, such as problem-solving, decision-making, and higher-order thinking skills. The enhanced communication between brain regions supports better coordination and integration of cognitive processes, leading to more efficient information processing.
In summary, the thickening of the corpus callosum during adolescence improves adolescents' ability to process information by enhancing communication and coordination between the brain's left and right hemispheres. This developmental change contributes to the cognitive advancements observed during this stage of life.
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The following are four electrical components.
A. A component which obeys ohm's law
B. Another component which obeys ohm's law
but which has higher resistance than A
A filament lamp
C.
D. A component, other than a filament lamp,
which does not obey ohm's law.
a. For each of these components, sketch current-
voltage characteristics, plotting current on the
vertical axis, and showing both positive and
negative values. Use one set of axes for A and
B, and separate sets of axes for C and for D.
label your graphs clearly.
b.
Explain the shape of the characteristic for C
c. Name the component you have chosen for D.
For the following are four electrical components:
a. For components A and B, both of which obey Ohm's law, the current-voltage characteristics would be a straight line passing through the origin. The slope of the line for component B would be steeper than that of component A, indicating higher resistance.
b. The shape of the characteristic for component C, the filament lamp, can be explained by its construction. A filament lamp consists of a filament made of a resistive material, typically tungsten, which heats up and emits light when an electric current passes through it.
c. The component chosen for D, which does not obey Ohm's law, could be a diode. A diode is a two-terminal electronic component that allows the current to flow in only one direction.
For the following are four electrical components:
a. Sketches of current-voltage characteristics:
For components A and B, both of which obey Ohm's law, the current-voltage characteristics would be a straight line passing through the origin. The slope of the line for component B would be steeper than that of component A, indicating higher resistance.
Current (I)
^
| B
| /
| /
| /
| /
| /
| /
| /
| /
| /
|/
+------------------> Voltage (V)
Current (I)
^
| A
| /
| /
| /
| /
| /
| /
| /
| /
| /
|/
+------------------> Voltage (V)
For component C, a filament lamp, the current-voltage characteristic would be a curve that is not linear. It would exhibit a non-linear increase in current with increasing voltage. At lower voltages, the lamp would have low resistance, but as the voltage increases, the resistance of the filament also increases due to the phenomenon of thermal self-regulation. This leads to a slower increase in current at higher voltages.
For component D, a component that does not obey Ohm's law, the current-voltage characteristic could be any non-linear curve depending on the specific component chosen. Examples of components that do not obey Ohm's law include diodes and transistors.
b. The shape of the characteristic for component C, the filament lamp, can be explained by its construction. A filament lamp consists of a filament made of a resistive material, typically tungsten, which heats up and emits light when an electric current passes through it. As the voltage across the filament increases, the temperature of the filament increases as well, causing its resistance to increase. This increase in resistance results in a slower increase in current with increasing voltage, leading to the characteristic non-linear curve observed.
c. The component chosen for D, which does not obey Ohm's law, could be a diode. A diode is a two-terminal electronic component that allows the current to flow in only one direction. It exhibits a non-linear current-voltage characteristic where it conducts current only when the voltage is above a certain threshold, known as the forward voltage. Below this threshold, the diode has a high resistance and blocks current flow in the reverse direction. The characteristic curve of a diode would show negligible current flow until the forward voltage is reached, after which it exhibits a rapid increase in current with a relatively constant voltage.
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2. The kinetic energy of an 1100-kg truck is 4.6 105 J. What is the speed of the truck? (A)25 m/s (B) 29 m/s (C) 21 m/s (D)33 m/s (E) 17 m/s
Answer:
(B) 29 m/s
Explanation:
The kinetic energy (KE) of an object can be calculated using the equation:
KE = (1/2) * m * v^2
where KE represents the kinetic energy, m represents the mass of the object, and v represents the velocity of the object.
Given that the mass of the truck is 1100 kg and the kinetic energy is 4.6 × 10^5 J, we can rearrange the equation to solve for the velocity (v):
KE = (1/2) * m * v^2
Solving for v:
v^2 = (2 * KE) / m
v^2 = (2 * 4.6 × 10^5 J) / 1100 kg
v^2 = 8.36 × 10^2 m^2/s^2
Taking the square root of both sides, we find:
v = √(8.36 × 10^2 m^2/s^2)
v ≈ 28.9 m/s
The speed of the truck is approximately 28.9 m/s.
Among the given options, the closest value to 28.9 m/s is (B) 29 m/s.
A 0.842g sample of Hydrogen 3 decays until 0.0526g remains. How many half lives have occurred?
A 0.842g sample of Hydrogen-3 decays to 0.0526g. Approximately 4.206 half-lives have occurred.
To determine the number of half-lives that have occurred, we can use the decay equation and the concept of exponential decay. The decay equation for radioactive decay is given by:
N(t) = N₀ * (1/2)^(t/T),[tex](1/2)^(^t^/^T^),[/tex]
where N(t) is the remaining amount of the substance at time t, N₀ is the initial amount, t is the time elapsed, and T is the half-life of the substance.
In this case, we have an initial mass of 0.842g (N₀) and a remaining mass of 0.0526g (N(t)). We can set up the equation as follows:
0.0526g = 0.842g [tex]* (1/2)^(^t^/^1^2^.^3^2)[/tex],
where t represents the number of half-lives that have occurred.
To solve for t, we can take the logarithm of both sides of the equation:
log(0.0526g/0.842g) = log[tex][(1/2)^(^t^/^1^2^.^3^2^)[/tex]].
Using the logarithmic property log([tex]a^b[/tex]) = b*log(a), we can rewrite the equation as:
log(0.0526g/0.842g) = (t/12.32) * log(1/2).
Simplifying further:
log(0.0526g/0.842g) = (t/12.32) * (-log2),
where log2 is the logarithm base 2.
Now, we can solve for t:
t = (12.32 * log(0.0526g/0.842g)) / (-log2).
Using the given values and performing the calculation, we find:
t ≈ 4.206.
Therefore, approximately 4.206 half-lives have occurred.
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1. The kinetic energy of a car is 8 106 J as it travels along a horizontal road. How much work is required to stop the car in 10 s? (A) zero joules (B) 8 105 J (C) 8 107 J (D)8 104 J (E) 8 106 J
The power to stop the car with kinetic energy of a car is [tex]8*10^{6} J[/tex] as it travels along a horizontal road is [tex]8*10^{5} watt[/tex], option B
What is Kinetic energy ?Kinetic energy can be seen as one that is been recorded when an object is able to move from a place , in a broad term we can say this is the energy that can be attributed to that of someone leaving a place and go to another place hence we can see it as the one in the motion.
The definition of energy as the "power to accomplish work" refers to the capacity to apply a force that moves an object. Even if the word is vague, it is clear what energy actually means: it is the force that causes objects to move. The two types can be attributed to the one we know which are kinetic and potential energy.
[tex]Power \frac{Energy}{time}[/tex]
[tex]Energy = 8*10^{6} J[/tex]
[tex]time = 10 s[/tex]
[tex]Power = \frac{8*10^{6} J}{10}[/tex]
[tex]power = 8*10^{5} watt[/tex]
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proper question;
The kinetic energy of a car is 8 × 106 J as it travels along a horizontal road. How much power is required to stop the car in 10 s? (A) zero joules (B) 8 105 J (C) 8 107 J (D)8 104 J (E) 8 106 J
Two loudsspeakers emit identical sound waves along the x axis. THe osund at a point on the axis has maximum intensity when the speakers are 40 cm apart. The sound intensity decreases as the distance between the speakers is increased, reaching zero at a separation of 50 cm. If the distance between the speakers continuse to increase, at what separation will the sound intensity again be a maximum?
Answer: 30 cm.
Solving
The situation described is that of two sources of sound waves that are separated by some distance. The two waves interfere with each other constructively at some points and destructively at others. When they interfere constructively, the amplitude (and intensity) of the sound wave is greater than when they interfere destructively.
When the speakers are 40 cm apart, the waves that they produce are in phase at some points on the axis, leading to constructive interference and a maximum in the intensity of the sound. As the distance between the speakers is increased beyond 40 cm, the points of constructive interference move farther apart, and the intensity of the sound decreases. When the speakers are 50 cm apart, the waves that they produce are exactly out of phase at some points on the axis, leading to complete destructive interference and a minimum in the intensity of the sound.
If the separation between the speakers continues to increase, the points of constructive interference will move closer together again, and the intensity of the sound will increase. The separation between the speakers at which the intensity of the sound will again be a maximum can be found using the following equation:
d = λ/2 + nλ
where d is the separation between the speakers, λ is the wavelength of the sound wave, and n is an integer that represents the number of half-wavelengths between the speakers.
At the maximum, the separation is an even multiple of half the wavelength, so we can use the formula above with n = 1. The wavelength can be found from the distance between the speakers at the minimum, which is 50 cm, and the distance at the maximum, which is 40 cm:
λ = 2(d_max - d_min) = 20 cm
Substituting λ and n into the formula gives:
d = λ/2 + nλ = 10 cm + 20 cm = 30 cm
Therefore, the sound intensity will be a maximum again when the separation between the speakers is 30 cm.
How are magnetic fields like vectors?
Answer:Magnetic fields from two sources add up as vectors at each point, so the strength of the field is not necessarily the sum of the strengths1. Magnetic fields are vectors, which means they have direction as well as size. Therefore, the sum of two magnetic fields is not simply the sum of their magnitudes2.
Explanation:
If a region of the Sun is brightest at a wavelength of 853 nm, what is the temperature (in K) of this region?
Answer:
3400 K
Explanation:
use wiens displacement law
λ_max = 853 nm = 853 × 10^−9 m
T = b / λ_max
substiute
T = (2.898 × 10^−3 m·K) / (853 × 10^−9 m)
T = 2.898 × 10^−3 / 853 = 3.4 × 10^3 K
Collimation of the x ray beam:
A: reduces scatter radiation and unnecessary exposure to the x ray beam
B: should be done to expose as large an area as possible
C: turns the beam at a 90 degree angle to x ray patients that are standing
D: both A and B
The collimation of the x-ray beam reduces scatter radiation and unnecessary exposure to the x-ray beam, and should be done to expose as large an area as possible (option d).
1. Collimation of the x-ray beam is an essential technique used in radiology to control the size and shape of the x-ray field.
2. One of the primary purposes of collimation is to reduce scatter radiation, which refers to the radiation that scatters in various directions within the patient's body. By limiting the size of the x-ray beam to the area of interest, collimation helps minimize scatter radiation, which can be harmful and reduce image quality.
3. Another crucial aspect of collimation is to minimize unnecessary exposure to the patient. By narrowing down the x-ray beam to the specific area being examined, areas outside the field of interest receive less radiation, reducing the patient's overall exposure.
4. It is important to note that collimation should be done to expose as large an area as possible while still maintaining adequate coverage of the region of interest. This ensures that the relevant structures are included in the x-ray image, providing valuable diagnostic information.
5. The statement that the collimation turns the beam at a 90-degree angle to x-ray patients that are standing (option C) is incorrect. Collimation does not involve changing the direction of the x-ray beam but rather controlling its size and shape.
6. The correct answer is option D: Both A and B. Collimation reduces scatter radiation and unnecessary exposure while also aiming to expose as large an area as possible, ensuring optimal imaging and patient safety.
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Three components in a parallel circuit have individual resistance of r-1 r-2 and r-3 what formula can you use to determine the total resistance of the circuit ?
In a parallel circuit, the total resistance (Rt) can be determined using the following formula:
1/Rt = 1/r1 + 1/r2 + 1/r3
where r1, r2, and r3 are the individual resistances of the components in the parallel circuit.
By taking the reciprocal of each resistance, adding them together, and then taking the reciprocal of the sum, you can find the total resistance of the parallel circuit.
I hope this helps. Cheers! ^^