Which is a characteristic of diatoms?
A)whip-like tail
B)heterotrophic
C)multicellular
D)glass-ive cell wall
Answer:
b
Explanation:
Answer:
The correct answer is D, diatoms have glass-like cell walls.
Explain how an electrical current is produced.
Answer:electric current can be generated by moving a metal wire through a magnetic field .electric current can also be produced by batteries
Explanation:
electric current can be generated by moving a metal wire through a magnetic field.this method is applicable in electric generators.
Electric current can also be generated by connecting metal wires to batteries.
What is the major difference between herbal and conventional medicines
The Palo Verde nuclear power generator of Arizona has three reactors that have a combined generating capacity of 3.937×109 W . How many years would it take the Palo Verde nuclear power generator to produce the same amount of energy as the Sun does in one day? The energy generation rate, or luminosity, of the Sun is 3.839×1026 W
Answer:
t = 2.68 x 10¹⁴ years
Explanation:
First we need to find the amount of energy that Sun produce in one day.
Energy = Power * Time
Energy of Sun in 1 day = (3.839 x 10²⁶ W)(1 day)(24 hr/1 day)(3600 s/ 1 hr)
Energy of Sun in 1 day = 3.32 x 10³¹ J
Now, the time required by the nuclear power generator, in years, will be:
Energy of power generator = Energy Sun in 1 day = 3.32 x 10³¹ J
3.32 x 10³¹ J = Power * Time
3.32 x 10³¹ J = (3.937 x 10⁹ W)(t years)(365 days/1 year)(24 hr/1 day)(3600 s/ 1 hr)
t = 3.32 x 10³¹ /1.24 x 10¹⁷
t = 2.68 x 10¹⁴ years
3. The current in a flashlight powered by 4.5 Volts is 0.5 A. What is the power delivered to the flashlight?
4.If the flashlight in the previous problem is left on for 3 minutes, how much electric energy is delivered to the bulb?
Answer:
Question 3: 2.25 watts
Question 4: 405 joules
Explanation:
question 3:
Current =0.5 amps
Voltage =4.5 volts
Power= current x voltage
Power=0.5 x 4.5
power=2.25 watts
Question 4
Current =0.5 amps
Voltage =4.5v
Time=3 minutes
Time =3x60
Time =180 seconds
Energy=current x voltage x time
Energy =0.5 x 4.5 x 180
Energy =405 joules
Visible light travels in air, which has an index of refraction of 1.0. It is incident on plastic which is covered by a coating (such that light hits the coating before the plastic). The coating has an index of refraction of 1.6 and is 0.50 microns thick. The ray reflected off the air-coating interface and the ray reflected off the coating-plastic interface experience interference. What frequencies could the light be
Answer:
λ = 0.64 10⁻⁶ m = 640 nm
Explanation:
The two reflected rays experience constructive interference, if we can see them, so we can one condition for interference, but let's see two phenomena that occur
* A ray when it is reflected by a surface of major spare part index has a phase change of 180º, these passes at the air-plastic interface
* A ray when passing a material with a refractive index changes its wavelength
λ= λ₀ / n
taking into account these facts the condition in constructive interference is
2 n t = (m + ½) λ
λ= 2 n t / (m + ½)
if we suppose that we have the first inference m = 0
λ = 2 1.6 0.5 10⁻⁶ (0 + ½)
λ = 3.2 10⁻⁶ m
this wavelength is in the infrared
suppose an interference of m = 1
λ = 1.6 10⁻⁶ / (1 + 1/2)
λ = 1.06 10-6 m
m = 2
λ = 1.6 10⁻⁶ / (2 + 1.5)
λ = 0.64 10⁻⁶ m
this wavelength corresponds to the visible range (640 nm) orange
Two astronomers are discussing supernovas. Dr. Frank says, "Research has established that if a supernova occurs within ten light-years of the Earth, then life on Earth will be destroyed." Dr. Harris says, "Research has also established that either a supernova will not occur within ten light-years of the Earth or life on Earth will not be destroyed." Is it possible that both astronomers are correct? If so, what can we determine about the occurrence of a supernova?
Answer:
Supernovae produce intense flashes of light that can last from several weeks to several months. They are characterized by a rapid increase in light intensity until reaching an absolute magnitude greater than the rest of the galaxy. Subsequently, its brightness decreases more or less smoothly until it disappears completely.
Explanation:
A team of international astronomers discovered that if the supernovae were found at a distance of 50 light years from Earth, they could cause the mass extinction of living things, according to an article published in the Astrophysical Journal.
"Until recently, our colleagues believed that the 'range' of supernovae was about 25 light years. We were of the opinion that they did not take into account a number of factors and that it is actually about 50 light years," Adrian said. Melott, from the University of Kansas at Lawrence (USA).
The unusually high power of cosmic rays in the atmosphere, according to Melott, results in an increase in the "damage radius" of supernovae. According to the researcher, supernova explosions are capable of destroying life within a radius of 50 light years and not 10 or 25 light years, as previously thought.
A cylindrical specimen of some metal alloy having an elastic modulus of 108 GPa and an original cross-sectional diameter of 3.7 mm will experience only elastic deformation when a tensile load of 1890 N is applied. Calculate the maximum length of the specimen before deformation if the maximum allowable elongation is 0.45 mm.
Answer:
L= 276.4 mm
Explanation:
Given that
E= 180 GPa
d= 3.7 mm
F= 1890 N
ΔL= 0.45 mm
We know that ,elongation due to load F in a cylindrical bar is given as follows
[tex]\Delta L =\dfrac{FL}{AE}[/tex]
[tex]L=\dfrac{\Delta L\times AE}{F}[/tex]
Now by putting the values in the above equation we get
[tex]L=\dfrac{0.45\times 10^{-3}\times \dfrac{\pi}{4}\times (3.7\times 10^{-3})^2\times 108\times 10^9}{1890}\ m[/tex]
L=0.2764 m
L= 276.4 mm
Therefore the length of the specimen will be 276.4 mm
Materials that allow electricity to pass through them are called ?
Answer:
Materials that allow electricity to pass through them are called conductors.
Copper wire is a good conductor. Materials that do not allow electricity to pass through them are called insulators.
Explanation:
Can I have brainliest?
(20) A rocket is launched vertically. At time t = 0 seconds, the rocket’s engine shuts down. At the time, the rocket has reached an altitude of 500m and is rising at a velocity of 125 m/s. Gravity then takes over. The height of the rocket as a function of time is h(t)=-9.8/2 t^2+125t+500,t>0. Using your function file from HW2A: Generate a plot of height (vertical axis) vs. time (horizontal axis) from 0 to 30 seconds. Include proper axis labels. Find the maximum height and the time at which it occurs: Analytically, showing your steps and equations. This part should be done entirely in the write-up: no coding Using the data cursor on the plot. Using the MAX function on your data from part (a) Using FMINSEARCH on your m file Comment on the differences between the methods. How closely does each method match the "true" (analytical) value? Find the time when the rocket hits the ground: Analytically, showing your equations. This part should be done entirely in the write-up: no coding Using the data cursor on the plot. Using FZERO on your m file Comment on the differences between the methods in each of part (B) and (C). How closely does each method match the "true" (analytical) value? Use a quantitative comparison to make your argument.
Answer:
Explanation:
Given that,
h(t) = -9.8t² / 2 + 125t + 500
for t > 0.
At t = 0, the rocket is at height h = 500m, at a velocity of Vo = 125m/s.
We want to find the maximum height reached by rocket
Using mathematics maxima and minima
let find the turning point when dh/dt = 0
dh/dt = -9.8t + 125
dh / dt = 0 = -9.8t + 125
9.8t = 125
t = 125 / 9.8
t = 12.76s
Let find the turning point to know if this time t = 12.76 is maximum or minimum point
Let find d²h / dt²
d²h / dt² = -9.8
Since, d²h/dt² < 0, then, at t = 12.76s is the maximum points.
Then, the maximum height reached is
h = -9.8t² / 2 + 125t + 500
h = -9.8(12.76)² / 2 + 125(12.76) + 500
h = -797.80 + 1595 + 500
h = 1297.2 m
The maximum height reached is 1297.2 m
From the attachment, the maximum height is 1297.2m at t = 12.76sec.
Comment, the result are the same for both the analysis aspect and the graphical aspect.
The greater the distance between two objects in space, the _______ their gravitational
Answer is Weaker. If it is talking about the objects' gravitational forces.
In a shipping company distribution center, an open cart of mass 50 kg is rolling to the left at a speed of 5 m/s. You can ignore friction between the cart and the floor. A 15 kg package slides down a chute that makes an angle of 27 degrees below the horizontal. The package leaves the chute with a speed of 3 m/s, and lands in the cart after falling for 0.75 seconds. The package comes to a stop in the cart after 4 seconds. What is:a) the speed of the package just before it lands in the cart
Answer:
Explanation:
The package leaves the chute with a speed of 3 m/s, and lands in the cart after falling for 0.75 seconds . During .75 second duration . package undergoes free fall due to which additional vertical velocity is added
velocity added = a x t
= 9.8 x .75
= 7.35 m /s
Total vertical velocity
= 3 sin27 + 7.35
= 8.71 m /s
Horizontal component = 3 cos 27
= 2.67 m /s
If v be the resultant velocity of these components
v² = 2.67² + 8.71²
v² = 7.13 + 75.86
v = 9.11 m /s .
In a double-slit interference experiment, which of the following actions (perhaps more than one) would cause the fringe spacing to increase? (a) Increasing the wavelength of the light. (b) Increasing the slit spacing. (c) Increasing the distance to the viewing screen. (d) Submerging the entire experiment in water
Answer:
The correct option is a , c
Explanation:
Generally the fringe spacing is mathematically defined as
[tex]y = \frac{m \lambda D}{d}[/tex]
Where y is the fringe spacing
m is the order of the fringe
[tex]\lambda[/tex] is the wavelength
D is the distance between the slit and the screen
d is the distance between the slit
Now in order to increase the fringe spacing can do the following
Increase the wavelength increase the distance from the slit to the screen Decrease the distance between the slitThe following action would increase the fringe spacing because the from the question these parameters are directly proportional to the fringe spacing
A piston with stops containing water goes through an expansion process through the addition of heat. State 1 the pressure is 200 kPa and the volume is 2 m3. After half of the heat has been delivered the piston hits the stops corresponding to a volume of 5 m3. After all the heat has been delivered, state 2, the pressure is 1000 kPa with the piston resting on the stops. What is the work?
Answer:
The work will be "600 kJ/kg".
Explanation:
(1-a) ⇒ Constant Pressure
(a-2) ⇒ Constant Volume
The given values are:
In state 1,
Pressure, P₁ = 200 kPa
Volume, V₁ = 2m³
In state 2,
Pressure, P₂ = 1000 kPa
Volume, V₁ = 5m³
Now,
In process (1-a), work will be:
⇒ W₁₋ₐ = P₁(Vₐ - V₁)
On putting the values, we get
⇒ W₁₋ₐ = 200(5-2)
⇒ = 200(3)
⇒ = 600 kJ/kg
In process (a-2), work will be:
⇒ Wₐ₋₂ = 0
∴ (The change in the volume will be zero.)
So,
⇒ Total work = (W₁₋ₐ) + (Wₐ₋₂)
⇒ = 600 + 0
⇒ = 600 kJ/kg
very thin 15.0 cm copper bar is aligned horizontally a l ong the east - west direction. If it moves horizontally from south to north at 11.5 m/s in a vertically upward magnetic field of 1.22 T, A) what potential difference is induced across its ends, and B) which end (east or west) is at a higher potential
Answer:
2.10 V
Explanation:
To find the potential difference across the ends of the bar, you take into account that when the bar moves with speed v, in a constant magnetic field, the charges in the wire feels a magnetic force that separate the opposite charges, generating an induced potential difference given by the following formula:
[tex]\epsilon=vBL[/tex] (1)
v: speed of the bar = 11.5 m/s
B: magnitude of the magnetic field = 1.22 T
L: length of the bar = 15.0cm = 0.15m
You replace the values of v, B and L in the equation (1):
[tex]\epsilon=(11.5m/s)(1.22T)(0.15m)=2.10\ V[/tex]
hence, the induced potential difference is 2.10 V
A skydiver just after leaping out of an airplane is it isinertial frames of reference or not?
Answer:
He starts accelerating until he reaches terminal speed. (Or the maximum velocity attainable by an object)
Explanation:
A Sense of Proportion: Saturn is about 60,000 km in radius, and its rings are only about 0.01 km thick with ripples 100m high. Design a really big model with Saturn 60 inches in radius (10 feet in diameter). How thick must the rings be in your model and how high can the ripples be
Answer:
The thickness of ring in model is 0.00001 inch and the height of ring is 0.0001 inch.
Explanation:
The radius of Saturn = 60000 km
The thickness of rings = 0.01 km
The height of ring ripples = 100 m or 0.1 km
Now design a new model with a radius of 60 inches.
Therefore, the radius of Saturn (600000 km) = radius of the model (60 inches)
Here, one inch of the model will be equal to 1000 km of Saturn.
1 km of Saturn = 0.001 inch of model
Thickness of ring = 0.01 km
Therefore, thickness of ring in model = 0.01 x 0.001 = 0.00001 inch
The height of Saturn ring = 0.1 km
Therefore, the height of ring in model = 0.1 x 0.001 = 0.0001 inch.
19
Which gas is the most abundant greenhouse gas?
A.
ozone
B.
chlorofluorocarbon
C.
carbon dioxide
OD.
methane
E.
water vapor
Reset
Next
Carbon dioxide is the most abundant greenhouse gas in the atmosphere.
Answer:C
Explanation:
Carbon dioxide is the most abundance greenhouse gas in The atmosphere.
An object has a mass of 5 kg. What force is needed to accelerate it at 6 m/s?
Answer:30N
Explanation:
Mass=5kg
Acceleration=6m/s^2
Force=mass x acceleration
Force=5 x 6
Force=30N
Answer:
30n
Explanation:
Mass=5kg
Acceleration=6m/s^2
Force=mass x acceleration
Force=5 x 6
Force=30N
Q8.(10 points) a)When you cough,the radius of your trachea (windpipe) decreases,affecting the speed of the air in the trachea. If 0 r is the normal radius of the trachea, the relationship between the speed S of the air and the radius r of the trachea during a cough is given by a function of the form 2 0 S r ar r r ( ) ( ) = − , where a is positive constant. Find the radius r for which the speed of the air is greatest
Answer:
[tex]\bf{r=\frac{2r_o}{3}}[/tex] is greatest
Explanation:
Given:
[tex]S(r)=ar^2(r_{o}-r)[/tex]
[tex]\frac{ds}{dr}=2ar(r_{o}-r)+ar^2(-1)[/tex]
[tex]\frac{ds}{dr}=2ar_{o}-2ar^2-ar^2[/tex]
[tex]\frac{ds}{dr}=2ar_{o}-3ar^2[/tex]
Substitute [tex]\frac{ds}{dr} = 0[/tex], so
[tex]2ar_{o}-3ar^2=0[/tex]
Then, get the common value from the equation.
[tex]ra(2r_{o}-3r) = 0[/tex]
[tex]\bf{r=0}\\r=\frac{2r_{o}}{3}[/tex]
[tex](\frac{d^2s}{dr^2})_{r=0}=2ar_{o}-6ar[/tex]
[tex](\frac{d^2s}{dr^2})_{r=0}=2ar_{o} >0\;and, \\(\frac{d^2s}{dr^2})_{r}=\frac{2r_o}{3} <0[/tex]
So, the speed of the air is greatest.
[tex]\bf{r=\frac{2r_o}{3}}\;is\;greatest[/tex]
Under electrostatic conditions, the electric field just outside the surface of any charged conductor
A. is always zero because the electric field is zero inside conductors
B. can have non zero components perpendicular to and parallel to the surface of the conductor
C. is always perpendicular to the surface of the conductor
D. is always parallel to the surface
E. is perpendicular to the surface of the conductor only if it is a sphere, a cylinder, or a flat sheet.
Answer:
C. is always perpendicular to the surface of the conductor
Explanation:
On a charged conductor , electric charge is uniformly distributed on its surface . The lines of forces are also uniformly distributed on all directions . They repel each other so they emerge perpendicular to the surface so that they do nor cut each other and at the same time they remain at maximum distance from each other.
11. Two radio antennas are 120 m apart on a north-south line, and they radiate in phase at a frequency of 3.4 MHz. All radio measurements are made far from the antennas. If the east-west reference line passes midway between the two antennas, what is the smallest angle in degree from the antennas, measured north of east, at which constructive interference of two radio waves occurs? (c = 3.00 × 108 m/s) (Input your answer in 2 significant figures without unit)
Answer:
47°
Explanation:
between the two antennas for an observer difference in length in quadrant I is
ΔL = dCos(θ)
setting θ=0 i.e the observer is north of the station to get
ΔL= d= 120 m.
The wavelength formula is:
λ = c / f = 3x [tex]10^8[/tex] / 3.4 x [tex]10^6[/tex] = 88.2m
Constructive interference occurs when the Length difference is equal to an integer multiple of a wavelength.
At the given spacing, and from an observation point north of the stations, they are more than a wavelength apart, so they are not in constructive interference. Looking for the first peak:
dCos(θ) = λ
Cos(θ) = λ/d
θ = arcCos(λ/d) = arcCos( 88.2 / 120 ) = 42.7°= 43°
For destructive interference:
90° - 43°= 47°
A fisherman fishing from a pier observes that the float on his line bobs up and down, taking 2.4 s to move from its highest point to its lowest point. He also estimates that the distance between adjacent wave crests is 48 m. What is the speed of the waves going past the pier?Immersive Reader
Answer:
v = 10 m / s
Explanation:
For this exercise we will use the relationship between the speed of a wave and its frequency and wavelength
v = λ f
the wavelength is the distance at which the wave repeats, in this case the distance between the two ridges λ = 48 m.
the frequency is the number of oscillations per unit of time, it is also the inverse of the period which is the time in a complete oscillation, in this case they give us the time of half a period, ½ T = 2.4 s
T = 4.8 s
the frequency is
f = 1 / T
f = 1 / 4.8
f = 0.2083 Hz
let's calculate
v = 0.2083 48
v = 10 m / s
What happens if you move a magnet near a could of wire
Answer:
The wire would stick to the magnet????????????????????????
Explanation:
The spaceship Lilac, based on the Purple Planet, is 721 m long when measured at rest. When the Lilac passes Earth, observers there measure its length to be 661 m. At what speed v is the Lilac moving with respect to Earth? Express your answer as a multiple of the speed of light c.
Answer:
The speed of Lilac is 0.399c.
Explanation:
The size of spaceship Lilac measured at the rest position = 721 m
The length of Lilac when it passes Earth = 661 m
Below is the calculation for speed at which Lilac is moving.
Here, L, is the length of spaceship when it passes the earth.
[tex]L_{0}[/tex] is the length of spaceship measured at rest.
V is the speed.
[tex]L = L_{0}\sqrt{1-\frac{v^{2}}{c^{2}}} \\[/tex]
[tex]1-\frac{v^{2}}{c^{2}} = \left ( \frac{L}{L_{0}} \right )^{2} \\[/tex]
[tex]\frac{v}{c} = \sqrt{1-\left ( \frac{L}{L_{0}} \right )^{2}} \\[/tex]
[tex]\frac{v}{c} = \sqrt{1-\left ( \frac{661}{721} \right )^{2}} \\[/tex]
[tex]v = 0.399c[/tex]
In later years, motors improved and could be run directly from a 60 Hz power supply. As a result, 25 Hz power systems shrank and disappeared. However, there were many perfectly-good working 25 Hz motors in factories around the country that owners were not ready to discard. To keep them running, some users created their own 25 Hz power in the plant using motor-generator sets. A motor generator set consists of two machines connected on a common shaft, one acting as a motor and the other acting as a generator. If the two machines have different numbers of poles but exactly the same shaft speed, then the electrical frequency of the two machines will be different due to Equation (3-34). What combination of poles on the two machines could convert 60 Hz power to 25 Hz power?
Answer:
as in motor generaror are connected to same shaft then both machines are working with same speed
but number of poles are different with same speed means both machines are working with different frequencies
we know
frequency F = N*P/120
speed N = 82120F/P
given
motor speed = generator speed
120F1/P1 = 120F2/P2
F1/P1 = F2/P2
output frequency is 25 which is obtained from generator so F2=25
input frequency is 60 which is given to motor soF1=60
60/P1 = 25/P2
60/25 = P!/P2
P1/P2 = 12/5
multiply and divided by 2 becuase poles are even
P1/P2 = 12*2/5*2
=24/10
P1= 24 poles a
P2 =10 poles we get 25 hz frequency from 60 hz frequency
A brick is dropped from a high scaffold. a. What is its velocity after 4.0s ?
b. How far does the brick fall during this time ?
Answer:
A: 1.962
B: 3.924
Explanation:
g = G *M /R^2
g = 9.807*M/R^2 the gravitational constant of ground level on earth is about 9.807
g = 9.807*5lbs/R^2 the average brick is about 5 pounds.
g = 9.807*5*10^2. I'm assuming the height is around ten feet to help you out.
with these numbers plugged in you get an acceleration of 0.4905 a final velocity after 4 seconds 1.962. It's height fallen after 4 seconds is 3.924.
( M = whatever the brick weighs it's not specified in the question)
(R = the distance from the ground or how high the scaffold is)
(hopefully you can just plug your numbers in there hope this helps)
A firearms company is testing a new model of rifle by firing a 7.50-g lead bullet into a block of wood having a mass of 17.5 kg. The bullet embeds into the block and the collision generates heat. As a consequence, the temperature rises by 0.040°C, as measured with a high-precision thermometer. Assuming that all the kinetic energy of the bullet goes into heating the system, what is the bullet’s speed when it enters the block? The initial temperatures of bullet and wooden block can be considered identical and the specific heats of lead and wood are cPb = 130 J/(kg ⋅ C°) and c wood = 1700 J/(kg ⋅ C°), respectively.
Answer:
Explanation:
Let the bullets speed be V .
Kinetic energy = 1/2 mV² where m is mass of bullet
This energy is converted into heat Q which raises the temperature of target by Δ T .
Q = mc Δ T , m is mass , c is specific heat and Δ T is rise in temperature .
heat absobed by bullet
= .0075 x 130 x .040
= .039 J
heat absorbed by block of wood
= 17.5 x 1700 x .04
= 1190 J
Total heat absorbed
= 1190.039 J
So kinetic energy = heat absobed
= 1/2 x .0075 x V² = 1190.039
V² = 317343.73
V = 563.33 m /s
Consider a disk, having mass and radius , that spins rapidly about an axle at its center, spinning with an angular velocity . The disk's axle is connected by a thin, massless rod of length to a central pivot. The end of the massless rod is fixed in place at that pivot, but it can freely rotate in all directions. 1) If the disk's mass and radius were each doubled, while keeping the other quantities (, , and ) fixed, by what factor would the rate of precession change? I.e., what is ?
Answer:
1/2
Explanation:
Solution:-
- The torque ( T ) induced at the pivotal point of the massless rod-disk assembly is given by:
T = M*g*r*sin ( θ )
Where,
M: The mass of the disk
r: the radius of the disk
θ: The precession angle
- The rate of change in angular momentum of the disk ( dL / dt ) is due to the induced torque ( T ) given by:
dL / dt = M*g*r*sin ( θ )
Hence,
dL = M*g*r*sin ( θ ). dt ... Eq1
- The change in precession angle ( dθ ) is a orthogonal component of change in angular momentum ( dL ) :
dθ = dL / ( L*sin ( θ ) ) ... Eq2
- Combine Eq1 and Eq2:
dθ = M*g*r*sin ( θ ). dt / ( L*sin ( θ ) )
dθ/dt = M*g*r / L ... Eq3
Where,
- The angular momentum of the disk is given by the product of moment of inertia ( I ) and angular velocity ( w ):
[tex]L = I*w\\\\L = \frac{1}{2}*M*r^2*w[/tex]
- Substitute the relationship of angular momentum of disk ( L ) into Eq3:
dθ/dt = M*g*r / 0.5*M*r^2*w
- Hence, the rate of change of precession ( dθ/dt ) is given by:
dθ/dt = 2*g / r*w
- If we double the mass ( M to 2M ) there is no effect on the rate of change of precession ( dθ/dt ). However, if we double the radius of the disk the rate of precession ( dθ/dt ) is halved due to the inverse relationship between the rate of precession ( dθ/dt ) and radius of the disk.
Answer:The factor of change would be ( 1 / 2 ) of the initial rate of change in precession.
A landscaper is shopping for landscaping materials. She wants to use materials through which water flows easily.
Which materials should she choose? Select three options.
clay
gravel
granite
rocks with cracks
loosely packed soil
Next
Mark this and retum
Save and Exit
Submit
Answer:
He needs clay gravel and rocks with cracks
