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4 years ago

What 2 wave principles are illustrated by black car seats getting hot when the sun is shining through a window?

Physics

1 answer:

PIT_PIT [208]4 years ago

7 0

Answer:

1) black body radiation

2) Electromagnetic radiation through the window

Explanation:

Blackbody radiation is the radiation produced by heated objects, particularly from a blackbody. The car is heated by sunshine. Actually, everything is heated by sunshine, and the car being a blackbody object absorbs all radiation (visible light, infrared light, ultraviolet light, etc.) that falls on it. This also means that it will also radiate at all frequencies that heat energy produces in it.

Radiation from the Sun is absorbed, through the glass, by the inside of the car. That is why it helps to have tinted glass or use a screen on the windows while it is parked.

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A worker pushes a box across the floor to the right at a constant speed with a force of 25N. What

icang [17]

Answer:

Friction between the box and the floor is 25N to the left

Explanation:

There are two forces acting on the box along the horizontal direction:

- The force of push applied by the worker, in the forward direction, F

- The force of friction, $F_f$ , acting in the opposite direction (backward)

So the net force acting on the box is

$F_{net}=F-F_f$

According to Newton's second law of motion, the net force on an object is equal to the product between its mass (m) and its acceleration (a), so we can write:

$F_{net}=ma$

And so

$F-F_f = ma$

However, in this case the box is moving at constant speed; this means that its acceleration is zero:

$a=0$

Therefore we have:

$F-F_f=0$

Which means

$F_f=F$

And since we are told that

$F=25 N$

This means that the force of friction is also 25 N:

$F_f=F=25 N$

6 0

4 years ago

Read 2 more answers

A satellite orbiting above the earth needs no power source to keep orbiting the earth.

abruzzese [7]

Answer:

True

Explanation:

The earths gravitational pull keeps it consistent with its orbit.

8 0

3 years ago

Read 2 more answers

023 (part 1 of 2) 10.0 points

Annette [7]

Answer:

Part 1

The angular speed is approximately 1.31947 rad/s

Part 2

The change in kinetic energy due to the movement is approximately 675.65 J

Explanation:

The given parameters are;

The rotation rate of the merry-go-round, n = 0.21 rev/s

The mass of the man on the merry-go-round = 99 kg

The distance of the point the man stands from the axis of rotation = 2.8 m

Part 1

The angular speed, ω = 2·π·n = 2·π × 0.21 rev/s ≈ 1.31947 rad/s

The angular speed is constant through out the axis of rotation

Therefore, when the man walks to a point 0 m from the center, the angular speed ≈ 1.31947 rad/s

Part 2

Given that the kinetic energy of the merry-go-round is constant, the change in kinetic energy, for a change from a radius of of the man from 2.8 m to 0 m, is given as follows;

$\Delta KE_{rotational} = \dfrac{1}{2} \cdot I \cdot \omega ^2 = \dfrac{1}{2} \cdot m \cdot v ^2$

I = m·r²

Where;

m = The mass of the man alone = 99 kg

r = The distance of the point the man stands from the axis, r = 2.8 m

v = The tangential velocity = ω/r

ω ≈ 1.31947 rad/s

Therefore, we have;

I = 99 × 2.8² = 776.16 kg·m²

$\Delta KE_{rotational}$ = 1/2 × 776.16 kg·m² × (1.31947)² ≈ 675.65 J

3 0

3 years ago

____________ are manufactured by the brain to help relieve pain. Ventricles Epinephrines Endorphins Phalanges

VMariaS [17]

It's Endorphins. That's a pain killer produced by the brain.

5 0

3 years ago

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a gym consists of a rectangular region with a semi-circle on each end. if the perimeter of the room is to be a 200 m running tra

Nikolay [14]

The dimensions of the rectangle are:

l = 50 m

b = $100/\pi$ m

<h3>What is a perimeter in math?</h3>

The perimeter is the length of the outline of a shape. To find the perimeter of a rectangle or square you have to add the lengths of all the four sides.

<h3>How do we find a perimeter of a rectangle?</h3>

The perimeter of a rectangle,denoted by P is given by the formula, P=2l+2b, where l is the length and b is the breadth of the rectangle.

<h3>Given:</h3>

As per the question:

Perimeter of the room is given as P = 200 m

The region is rectangular having a semicircle at each end.

Now,

Let 'l' be the length of the rectangle, 'b' be its breadth and 'r' be the radius of the semi-circle at each end.

Then, Area of the given rectangle, A = lb

Perimeter of the room, P is = $\pi r+l+\pi r+l=2\pi r+2l=\pi b+2l$