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Tatiana [17]
3 years ago
8

To understand the formula for power radiated in the form of electromagnetic energy by an object at nonzero temperature. every ob

ject at absolute (kelvin) temperature t will radiate electromagnetic waves. this radiation is typically in the infrared for objects at room temperature, with some visible light emitted for objects heated above 1000 k. the formula governing the rate of energy radiation from a surface is given by p=eσat4, where p is the thermal power (also known as the heat current h). part a this formula applies to _______________. this formula applies to _______________. any object of total surface area a, kelvin temperature t, and emissivity e any object of cross-sectional area a, kelvin temperature t, and emissivity e any object of total surface area a, kelvin temperature t, and emissivity σ any object of cross-sectional area a, kelvin temperature t, and emissivity σ request answer part b
Physics
1 answer:
lbvjy [14]3 years ago
3 0

As per Stefan - Boltzmann law we know that

1. Power radiated in the form of electromagnetic energy by an object at nonzero temperature.

2. Every object at absolute (kelvin) temperature t will radiate electromagnetic waves.

3. This radiation is typically in the infrared for objects at room temperature, with some visible light emitted for objects heated above 1000 k.

4. The formula governing the rate of energy radiation from a surface is given by p=eσat^4,

where p is the thermal power (also known as the heat current h).

Thermal radiation in visible light can be seen on hot metalwork. Its emission in the infrared is invisible to the human eye. Infrared cameras are capable of capturing this infrared emission.

Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. Particle motion results in charge-acceleration or dipole oscillation which produce electromagnetic radiation.

Examples of thermal radiation include the visible light and infrared light emitted by an incandescent light bulb, the infrared radiation emitted by animals that is detectable with an infrared camera, and the cosmic microwave background radiation. Thermal radiation is different from thermal convection and thermal conduction—a person near a raging bonfire feels radiant heating from the fire, even if the surrounding air is very cold.

Sunlight is part of thermal radiation generated by the hot plasma of the Sun. The Earth also emits thermal radiation, but at a much lower intensity and different spectral distribution. The Earth's absorption of solar radiation, followed by its outgoing thermal radiation, are the two most important processes that determine the temperature and climate of the Earth in most climate models.

So the correct answer which is applicable here will be

This formula applies to any object of total surface area a, kelvin temperature t, and emissivity e

here

\sigma[\tex] = stefan boltzmann constant = [tex]5.67 * 10^{-8}

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The bigclaw snapping shrimp shown in (Figure 1) is aptly named--it has one big claw that snaps shut with remarkable speed. The p
leva [86]

1) 1.86\cdot 10^6 rad/s^2

2) 2418 rad/s

3) 27000 m/s^2

4) 36.3 m/s

Explanation:

1)

The angular acceleration of an object in rotation is the rate of change of angular velocity.

It can be calculated using the following suvat equation for angular motion:

\theta=\omega_i t +\frac{1}{2}\alpha t^2

where:

\theta is the angular displacement

\omega_i is the initial angular velocity

t is the time

\alpha is the angular acceleration

In this problem we have:

\theta=90^{\circ} = \frac{\pi}{2}rad is the angular displacement

t = 1.3 ms = 0.0013 s is the time elapsed

\omega_i = 0 is the initial angular velocity

Solving for \alpha, we find:

\alpha = \frac{2(\theta-\omega_i t)}{t^2}=\frac{2(\pi/2)-0}{0.0013}=1.86\cdot 10^6 rad/s^2

2)

For an object in accelerated rotational motion, the final angular speed can be found by using another suvat equation:

\omega_f = \omega_i + \alpha t

where

\omega_i is the initial angular velocity

t is the time

\alpha is the angular acceleration

In this problem we have:

t = 1.3 ms = 0.0013 s is the time elapsed

\omega_i = 0 is the initial angular velocity

\alpha = 1.86\cdot 10^6 rad/s is the angular acceleration

Therefore, the final angular speed is:

\omega_f = 0 + (1.86\cdot 10^6)(0.0013)=2418 rad/s

3)

The tangential acceleration is related to the angular acceleration by the following formula:

a_t = \alpha r

where

a_t is the tangential acceleration

\alpha is the angular acceleration

r is the distance of the point from the centre of rotation

Here we want to find the tangential acceleration of the tip of the claw, so:

\alpha = 1.86\cdot 10^6 rad/s is the angular acceleration

r = 1.5 cm = 0.015 m is the distance of the tip of the claw from the axis of rotation

Substituting,

a_t=(1.86\cdot 10^6)(0.015)=27900 m/s^2

4)

Since the tip of the claw is moving by uniformly accelerated motion, we can find its final speed using the suvat equation:

v=u+at

where

u is the initial linear speed

a is the tangential acceleration

t is the time elapsed

Here we have:

a=27900 m/s^2 (tangential acceleration)

u = 0 m/s (it starts from rest)

t = 1.3 ms = 0.0013 s is the time elapsed

Substituting,

v=0+(27900)(0.0013)=36.3 m/s

5 0
3 years ago
A cellphone charger has a transformer with 2000 turns in the primary coil which converts 240v a.c to 6v a.c and a rectifier that
inn [45]

Answer:

As we are converting 220V AC into a 5V DC, first we need a step-down transformer to reduce such high voltage. Here we have used 9-0-9 1A step-down transformer, which convert 220V AC to 9V AC. In transformer there are primary and secondary coils which step up or step down the voltage according to the no of turn in the coils.

Selection of proper transformer is very important. Current rating depends upon the Current requirement of Load circuit (circuit which will use the generate DC). The voltage rating should be more than the required voltage. Means if we need 5V DC, transformer should at least have a rating of 7V, because voltage regulator IC 7805 at least need 2V more i.e. 7V to provide a 5V voltage.

5 0
2 years ago
A 1,500-kg car accelerates along a flat track to a speed of 20 m/s. how much does it's gravitational potential energy increases
lesya [120]
Look at bitesizes physics section, they have all the information you need to complete this question.
3 0
3 years ago
Suppose a ball is dropped from shoulder height, falls, makes a perfectly elastic collision with the floor, and rebounds to shoul
Bezzdna [24]

Answer:Same magnitude

Explanation:

When ball is dropped from shoulder height h then velocity at the bottom is given by

v_1=\sqrt{2gh}

if it makes elastic collision then it will acquire the same velocity and riser up to the same height

If m is the mass of ball then impulse imparted is given by

J=m(v_2-v_1)

J=2m\sqrt{2gh}

Thus impulse imparted by gravity and Floor will have same magnitude of impulse but direction will be opposite to each other.

7 0
3 years ago
an athlete whirls an 8.71 kg hammer tied to the end of a 1.5 m chain in a simple horizontal circle where you should ignore any v
-BARSIC- [3]

Answer:

T = 692.42 N

Explanation:

Given that,

Mass of hammer, m = 8.71 kg

Length of the chain to which an athlete whirls the hammer, r = 1.5 m

The angular sped of the hammer, \omega=1.16\ rev/s=7.28\ rad/s

We need to find the tension in the chain. The tension acting in the chain is balanced by the required centripetal force. It is given by the formula as follows :

F=m\omega^2r\\\\=8.71\times (7.28)^2\times 1.5\\\\=692.42\ N

So, the tension in the chain is 692.42 N.

5 0
3 years ago
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