How does a concave mirror form an image

Answer:

In electromagnetic waves, energy is transferred through vibrations of electric and magnetic fields. In sound waves, energy is transferred through vibration of air particles or particles of a solid through which the sound travels. In water waves, energy is transferred through the vibration of the water particles.

Answer:

Explanation:

The box is at rest because , the component of weight along the surface downwards is equal to frictional force .

frictional force = mgsinθ

= 20 x 9.8 sin 30

= 98 N .

Answer:

I would say that the mutation has no effect on the organism, as it doesn't help or harm it.

hope this helps :)

OB

mmnjnjlkdhfutydjfyiudtkcgvyftdcgvjyiluftgyiuyu  ( had to do that cuz it wouldn't let through)

Answer:

20cal/s

Explanation:

Question:

There are two questions. The first one has been answered:

From the formular, Power = Q/t = (kA∆T)/l

the amount heat depends on the duration of time interval, length of the iron rod, the thermal conductivity of iron and the temperature difference between the ends of the rod.

The amount of heat that flows through the rod by conduction during a given time interval does not depend upon the mass of the iron rod (D).

Second question:

The ends of a cylindrical steel rod are maintained at two different temperatures. The rod conducts heat from one end to the other at a rate of 10 cal/s. At what rate would a steel rod twice as long and twice the diameter conduct heat between the same two temperatures?

Solution:

Power = 10cal/s

Power = energy per unit time = Q/t

Where Q = energy

Power = (kA∆T)/l

k = thermal conductivity of iron

A = area

Area = πr^2

r = radius

Diameter = d = 2r

r = d/2

Area = (πd^2)/4

Length = l

∆T = change in temperature

10 = (kA∆T)/l

For a steel rod with length doubled and diameter doubled:

Let Length (L) = 2l

Diameter (D)= 2d

Area = π [(2d)^2]/4 = (π4d^2)/4

Area = 4(πd^2)/4

Using the formula Power = (kA∆T)/l, insert the new values for A and l

Power = [k × 4(πd^2)/4 × ∆T]/2l

Power = [4k((πd^2)/4) ∆T]/2l

Power = [(4/2)×k((πd^2)/4) ∆T]/l

Power = [2k(A) ×∆T]/l = 2(kA∆T)/l

Power of a steel that has its length doubled and diameter doubled = 2(kA∆T)/l

Recall initial Power = (kA∆T)/l = 10cal/s

And ∆T is the same

2[(kA∆T)/l] = 2 × 10

Power of a steel that has its length doubled and diameter doubled = 20cal/s

Answer:

The extent of greenhouse effect on mars is [tex]G_m = 87 K[/tex]  

Explanation:

From the question we are told that

     The albedo value of Mars is  [tex]A_1 = 0.15[/tex]

      The albedo value of Mars is  [tex]A_2 = 0.15[/tex]

       The surface temperature of Mars is  [tex]T_1 = 220 K[/tex]

        The surface temperature of Venus is  [tex]T_2 = 700 K[/tex]

          The distance of Mars from the sun is [tex]d_m = 2.28*10^8 \ km = 2.28*10^8* 1000 = 2.28*10^{11} \ m[/tex]

          The distance of Venus from sun is  [tex]d_v = 1.08 *10^{8} \ km = 1.08 *10^{8} * 1000 = 1.08 *10^{11} \ m[/tex]

       The radius of the sun is [tex]R = 7*10^{8} \ m[/tex]

        The energy flux is   [tex]E = 6.28 * 10^{7} W/m^2[/tex]

The solar constant for Mars is mathematically represented as

          [tex]T = [\frac{E R^2 (1- A_1)}{\sigma d_m} ][/tex]

Where [tex]\sigma[/tex] is the Stefan's constant with a value  [tex]\sigma = 5.6*10^{-8} \ Wm^{-2} K^{-4}[/tex]

So substituting values

         [tex]T = \frac{6.28 *10^{7} * (7*10^8)^2 * (1-0.15)}{(5.67 *10^{-8}) * (2.28 *10^{11})^2)}[/tex]

          [tex]T = 307K[/tex]

So the greenhouse effect on Mars is  

           [tex]G_m = T - T_1[/tex]

           [tex]G_m = 307 - 220[/tex]

          [tex]G_m = 87 K[/tex]

Answer:

Question 1: 189 joules

Question 2: 2.25 watts

Question 3: 405 joules

Question 4: 0.00125 watts

Question 5: 450000 joules

Explanation:

question 1:

Volt=1.5v

Resistance =5 ohms

Time=7 minutes

Time=7 x 60

Time=420 seconds

Current =voltage ➗ resistance

Current =1.5 ➗ 5

Current =0.3 amps

Energy=current x voltage x time

Energy=0.3 x 1.5 x 420

Energy =189 joules

Question 2:

Current =0.5 amps

Voltage =4.5v

Power=current x voltage

Power=0.5 x 4.5

Power=2.25 watts

Question 3:

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

Question 4:

Resistance=50 ohms

Current =5 milliamps

Current =5/1000

Current =0.005 amps

Power =current x current x resistance

Power=0.005 x 0.005 x 50

Power=0.00125 watts

Question 5:

Power =50 watts

Time=2.5 hour

Time=2.5 x 60 x 60

Time =9000 seconds

Energy=power x time

Energy=50x9000

Energy=450000 joules

Answer:

The electric and magnetic fields gradually increase.

Explanation:

Time constant in RL circuits, denoted by τ, is equal to the value of L / R which is the value of the inductor over the resistor. It is used to calculate the point when the current will reach the maximum value in the steady state of the circuit. Because of this behavior of the circuit, the magnetic field and the electric field gradually increase to their maximum values.

I hope this answer helps.

Answer:

t = 0.029 s

Explanation:

We have,

Speed of sound is 343 m/s.

Dezeirey is positioned 5 m behind her.

It is required to find the time taken for the echo from the wall to reach her. The total distance covered by the echo when it reaches her is 2d or 10 m.

Time taken,

[tex]t=\dfrac{d}{v}\\\\t=\dfrac{10\ m}{343\ m/s}\\\\t=0.029\ s[/tex]

So, it will take 0.029 seconds for the echo from the wall to reach her.

Answer:

A fan pushes hot air out of a vent and into a room. The hot air displaces cold air in the room, causing the cold air to move closer to the floor.

The hot air displacing the cold air is an example of  transfer by

Explanation:

also the answer is hit my dm on ig

Answer:

1. transverse

2. transverse

3. longitudinal

4. idk

Explanation:

1. longitudinal

2. transverse

3. longitudinal

4. transverse

Answer:

B. add more loops of wire between the magnets

Explanation:

this would increase the magnetic force acting on the rod therefore increasing

By adding more loops of wire between the magnets the motor is changed to be able to lift a heavier box.

An electric motor is a mechanism that turns electricity into mechanical energy.

The interaction between the motor's magnetic field and electric current in a wire winding generates force in the form of torque imparted to the motor's shaft in most electric motors.

An electric generator is physically equivalent to an electric motor, but it converts mechanical energy into electrical energy using a reversed flow of power.

The load capacity in the motor can be increased by increasing the no of loops. So by adding more loops of wire between the magnets the motor is changed to be able to lift a heavier box.

Hence option B is correct.

To learn more about the electric motor refer to the link;

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Answer:

The first flashlight,

P = 7.5 W

The second flashlight,

P = 18.75 W

Explanation:

P = VI.................. Equation 1

Where P = Power, V = Voltage, I = current.

For the first flashlight,

Given: I = 2.5 A, and V = 1.5×2 (The first uses two battery in chain) = 3 V

Substitute into equation 1

P = 3(2.5)

P = 7.5 W.

For the second flash light,

P = VI

Given: I = 2.5 A, V = 1.5×5 ( The second uses five batteries in a chain) = 7.5 V

Substitute into equation 1

P = 2.5(7.5)

P = 18.75 W.

Answer:

The horizontal distance between two adjacent crests or troughs is known as the wavelength.

Answer: Wavelength

Explanation:

From crest to crest, it is one full wavelength

Answer:

Explanation:

Emf e generated in a coil with no of turn n and area A rotating in a magnetic field B  with angular speed of ω is given by the expression

e = e₀ sinωt

where e₀ = nωAB which is the maximum emf generated

Putting the given values

15.7 = 1000xω x 20 x 10⁻² x 5

ω = .0157

frequency of rotation

= ω / 2π

= .0157 / 2 x 3.14

= .0025 /s

9 rotation / hour .

Answer:

Check the explanation

Explanation:

Part A

F = CA

this drag force balances the weight = 6X 9.8

so

6X9.8 = 0.5 X A X0.5 X 1.2 X 532

A= 0.069 m2

Part B

here the sorce is moving and the observer is at rest

so f= f(- 1 - 1

f = 1.1X10 343 343 – 53

f' = 1.3 KHz

Part C:

given the intensity = 30 dB

we know that I dB = 10 log (I(W/m2))

so we get I (W/m2) = 1000

Part D : The catch

Given that U1 = 53 M1 = 6 kg

U2 =-10 M2=0.25

V1=V2

now conserving momentum

6 X 53 -0.25 X10 =(6+0.25)V

V= 50.48 m/sec

Answer:

Mass

Explanation:

Mass is the measure of amount of matter contained within any substance and hence mass determines the weight. Unit of mass is kilogram as per ISI system of units.  

Mass is measured through a balance. The more is the mass of an object, the more the balance tilts towards the object side.  

Weight is equal to product of mass and the gravitational constant i.e 9.8m/s^2

Answer:

(C) is correct option.

Explanation:

The loudness of sound wave determines its amplitude. If the sound is loud, it will have more amplitude while if the sound is soft, it will have less amplitude.

On doubling the amplitude of sound wave, it will become more loud.

Doubling the amplitude of a sound wave will leave the speed of sound unchanged, but cause the sound to be louder. Hence, the correct option is (C).

Answer:

1.47*10^{-8}s

Explanation:

You first calculate the distance traveled by the electron:

[tex]x=vt\\\\x=(0.941(3*10^8m/s))(15.7*10^{-9}s)=4.43m[/tex]

Next, you calculate the relative speed as measure by an observer in the positron, of the electron:

[tex]u'=\frac{u+v}{1+\frac{uv}{c^2}}\\\\u'=\frac{0.941c+0.941c}{1+\frac{(0.941)^2c^2}{c^2}}\\\\u'=0.99c[/tex]

with this relative velocity you calculate the time:

[tex]t=\frac{x}{u'}\\\\t=\frac{4.43m}{0.99c}=1.47*10^{-8}s[/tex]

Answer:0.2 m/s^2

Explanation:

mass=18.15kg

Force=3.63N

Acceleration=force ➗ mass

Acceleration=3.63 ➗ 18.15

Acceleration=0.2 m/s^2

A girl pushes a wagon of mass 18.15 kg with a force of 3.63 N, so the acceleration of the wagon will be 0.2 m/s².

In mechanics, acceleration is the measure of how rapidly an object's velocity changes over time. Accelerations as a vector quantity. An object's acceleration depends on the direction of the net force exerted on it.

A vector quantity, acceleration, is something that has both a magnitude and a direction. As a vector quantity, velocity is also. The ratio of the velocity vector change over a time interval to that interval is the definition of acceleration.

Mass, m =18.15 kg

Force, f = 3.63 N

Force = m × a

a= f / m

a =3.63 / 18.15

a = 0.2 m/s²

Hence, the acceleration of the wagon will be 0.2 m/s².

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Answer:

a) t = 9.16*10^{-18} s

b) y = 0.402 mm

Explanation:

(a) To find the time that the particle takes to pass trough the region between parallel plates, you take into account that the horizontal component of the velocity is constant in all trajectory of the particle. Then, you use the following formula:

[tex]t=\frac{x}{v_x}\\\\[/tex]

x: length of the sides of the plates = 0.22m

v_x: horizontal component of the velocity = 2.4*10^6 m/s

[tex]t=\frac{0.22m}{2.4*10^6m/s}\\\\t=9.16*10^{-8}s=91.6ns[/tex]

(b) To find the vertical displacement of the particle you first calculate the acceleration of the particle generated by the electric force:

[tex]F_e=ma\\\\qE=ma\\\\a=\frac{qE}{m}\\\\a=\frac{(1.6*10^{-19}C)(33*10^3N/C)}{5.5*10^{-26}C}=9.6*10^{10}\frac{m}{s^2}[/tex]

where you have used that the charge is 1.6*10^-19 C (charge of an electron).

With the values of the acceleration and time you use the following kinematic equation to calculate the vertical displacement:

[tex]y=v_{oy}t+\frac{1}{2}at^2\\\\v_{oy}=0m/s\\\\y=\frac{1}{2}(9.6*10^{10}\frac{m}{s^2})(9.16*10^{-8}s)^2=4.02*10^{-4}m=0.402mm[/tex]

Following are the solution to the given points:

When calculating the time required the particle will pass through the zone between plates, remember that such a horizontal component of the particle's velocity is fixed throughout the particle's route. The following formula is then used:

            [tex]\to t=\frac{x}{v_x}[/tex]

           [tex]\to x:[/tex] plate length = 0.22m

           [tex]\to v_x :[/tex]velocity's horizontal component[tex]= 2.4\times 10^{6} \ \frac{m}{s}\\\\[/tex]

           [tex]\to t=\frac{0.22\ m}{ 2.4 \times 10^6 \frac{m}{s}}= 9.16 \times 10^{-8} \ s = 91.6 \ ns[/tex]

          [tex]\to F_e=ma\\\\\to qE=ma\\\\\to a=\frac{qE}{m}\\\\[/tex]

                 [tex]=\frac{1.6 \times 10^{-19}\ C \times 33 \times 10^3 \frac{N}{C}}{5.5 \times 10^{-26} C} \\\\ =\frac{1.6 \times 10^{-16} \times 33 \times 10^{26}}{5.5} \\\\ =\frac{1.6 \times 33 \times 10^{10}}{5.5} \\\\ =\frac{16 \times 33 \times 10^{10}}{55} \\\\ = 9.6 \times 10^{10} \ \frac{m}{s^2}\\\\[/tex]

           [tex]\to y=v_{oy} t+\frac{1}{2} at^2\\\\\to v_{oy}= 0 \ \frac{m}{s}\\\\\to y=\frac{1}{2} (9.6 \times 10^{10} \frac{m}{s^2}) (9.6 \times 10^{-8}\ s)^2[/tex]

                  [tex]= 4.02 \times 10^{-2} \ m \\\\ = 0.402 \ mm\\\\[/tex]

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Answer: Holdfast is a root- like structure by which an aquatic sessile algae are attached to a substrate. Its primary function is to secure the organism to the sea floor, i.e anchorage.

Answer:A

Explanation:

The crust Of The earth's has plates boundaries,when the layers that forms to boundaries glide on each other, vibrations occur which are known as earthquakes

Answer:

A) Can be Broken Into Many Plates

Answer:

distance

Explanation:

Speed is the rate of change of position expressed as distance travelled per unit of time

Answer:

Flying cars.

Explanation:

Answer:depends on the masses of the objects and the distance between them

Explanation:

According to Newton's law of universal gravitation,the force of attraction between two objects depends on the masses of the objects and the distance between them

Answer:

18

Explanation:

got it right on edge

Answer:Velocity

Explanation:

Velocity is directly proportional to the frequency of a wave.

Velocity=frequency x wavelength