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3 years ago

In most materials, as heat energy is absorbed, density

Physics

1 answer:

PtichkaEL [24]3 years ago

5 0

Answer:

In most materials, as heat energy is absorbed, the density decreases. IF a certain object is heated, it might appear bigger than usual because it expands as the molecules inside moves faster than usual. However the mass of it stays the same while the density decreases.

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A 7.0kg skydiver is descending with a constant velocity

Vikentia [17]

Answer:

The air resistance on the skydiver is 68.6 N

Explanation:

When the skydiver is falling down, there are two forces acting on him:

- The force of gravity, of magnitude $mg$ , in the downward direction (where m is the mass of the skydiver and g is the acceleration due to gravity)

- The air resistance, $R$ , in the upward direction

So the net force on the skydiver is:

$F=mg-R$

where

m = 7.0 kg is the mass

$g=9.8 m/s^2$

According to Newton's second law of motion, the net force on a body is equal to the product between its mass and its acceleration (a):

$F=ma$

In this problem, however, the skydiver is moving with constant velocity, so his acceleration is zero:

$a=0$

Therefore the net force is zero:

$F=0$

And so, we have:

$mg-R=0$

And so we can find the magnitude of the air resistance, which is equal to the force of gravity:

$R=mg=(7.0)(9.8)=68.6 N$

6 0

4 years ago

A student with a mass of 65.5 kg runs up a flight of 18 stairs. Each of the steps has a height of 16.5 cm. The student was able

Helga [31]

The power developed by the student is 756.9 J/s and remains the same if the student takes the same time to climb the stairs when climbing it in two's and three's.

<h3>What is power?</h3>

Power is the rate at work is done.

Power = work done/time
work done = mass × acceleration due to gravity × height

Work done = 65.5 × 10 × (18 × 0.165) = 1945.35 J

Power = 1945.35/2.57 = 756.9 J/s

If the student climbed the steps in two or three at a time, the power does not change if the time remains the same.

Time required = Energy/ power

The time required to convert the Big Mac meal from McDonalds = 4 853 440/756.9

Time required = 6412.26 seconds

Therefore, from the power developed by the student, it will take him 6412.26 seconds to convert all the energy in a Big Mac meal.

Learn more about power at: brainly.com/question/1634438

#SPJ1

5 0

2 years ago

Write a use of magnetic force and frictional force each

Firdavs [7]

Magnetic force:Computer hard drives use magnetism to store the data on a rotating disk. More complex applications include: televisions, radios, microwave ovens, telephone systems, and computers. ... Frictional force:Quite often uses of friction can be seen from how things would be without friction.

7 0

3 years ago

Which of the following is a problem with the estimated age of the universe?

dolphi86 [110]

Answer:

The Earth is 4.543 billion years old

3 0

3 years ago

Tidal friction is slowing the rotation of the Earth. As a result, the orbit of the Moon is increasing in radius at a rate of app

melomori [17]

Answer:

967500000 years