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3 years ago

Which of the following are true concerning Newton's Law Of Gravitation?

Physics

1 answer:

gogolik [260]3 years ago

4 0

Answer:

Explanation:

I think these are the answers

1) True: The gravitational force between two objects depend on their masses and distance.

2) True: The gravitational force between objects is always attractive, meaning the force vectors will always point towards each other. (think Newton's 3rd law)

3)True: There will always be some sort of gravitional attraction between objects although it would be close to 0 for small objects.

4)False: the force applied on each object are equal (remember: Newton's 3rd law).

5)False: The further the satellite is from the surface of a planet, the weaker the gravitional force is between them. The force is a max at the surface of the planet.

6)False:(same as 5's explaination)

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A car moving at 10 m/s crashes into a large bush and stops in 1.3 m. Using the Work-Energy theorem, calculate the average force

ad-work [718]

Answer:

The magnitude of the average force the seat belt exerts on the passenger is 2692.3 N.

It takes 0.26 s to bring the passenger in the car to a halt.

Explanation:

Hi there!

The negative work (W) needed to bring a moving object to stop is equal to its kinetic energy (KE):

W = KE

F · s = 1/2 · m · v²

Where:

F = applied force on the passenger.

s = displacement of the passenger.

m = mass of the passenger.

v = velocity of the passenger.

Solving the equation for F:

F = 1/2 · m · v² / s

Replacing with the data:

F = 1/2 · 70 kg · (10 m/s)² / 1.3 m

F = 2692.3 N

The magnitude of the average force the seat belt exerts on the passenger is 2692.3 N.

According to the second law of Newton:

F = m · a

Where "a" is the acceleration of the passenger.

We also know from kinematics that the velocity of an object can ve calculated as follows:

v = v0 + a · t

Where:

v = velocity of the passenger at time t.

v0 = initial velocity.

t = time.

a = acceleration.

When the passenger stops, its velocity is zero. So replacing a = F/m, let´s solve the equation for the time it takes the passenger to stop:

v = v0 + a · t

0 = 10 m/s + (-2692.3 N/ 70 kg) · t

-10 m/s / (-2692.3 N/ 70 kg) = t

t =0.26 s

It takes 0.26 s to bring the passenger in the car to a halt.

5 0

3 years ago

the particles that make up a rock are constantly in motion however a rock does not visibly vibrate. why do you think this?

Ivahew [28]

I think this is because the particles don't know or care about each other,
and they act completely without any peer pressure. The direction in which
any one particle vibrates is completely random, and there is no connection
or influence among the particles. That means that any direction is just as likely
as any other direction for the next vibration, and they all wind up vibrating in
different directions. There is a tiny tiny tiny tiny chance that all of them could
vibrate in the same direction for just an instant; if that ever happened, the rock
would suddenly jump up in the air. That's actually true, but the chance is so tiny
that it hasn't ever happened yet. In fact, the chance is so tiny, that when scientists
do their calculations of particle vibrations, they assume that the chance is zero,
and that makes the calculations simpler.

3 0

3 years ago

Compare these two collisions of a PE student with a wall.

Stolb23 [73]

1) The variable that is different in the two cases is $\Delta t$ , the duration of the collision

2) The change in momentum is the same in the two cases

3) The impulse is the same in the two cases

4) Case B will experience a greater force

Explanation:

The variable that is different in the two cases is $\Delta t$ , the duration of the collision.

In fact, in the first case the wall is padded: this means that the collision will be "softer" and therefore will last longer, so the duration of the collision, $\Delta t$ , will be larger.

In the second case instead, the wall is unpadded: this means that the collision is "harder" and so it will last less time, therefore the duration of the collision $\Delta t$ will be smaller.

The change in momentum in the two cases is the same.

In fact, the change in momentum is given by:

$\Delta p = m(v-u)$

where:

m is the mass of the student

u is the initial velocity

v is the final velocity

In both cases, we have:

m = 75 kg

u = 8 m/s

v = 0 (they both comes to rest)

Therefore, the change in momentum is

$\Delta p = (75)(0-8)=-600 kg m/s$

The impulse in the two cases is the same.

In fact, impulse is defined as the product of force applied, F, and duration of the collision, $\Delta t$ :

$J=F \Delta t$

However, the force can be rewritten as product of mass (m) and acceleration (a), according to Newton's second law:

$F=ma$

So the impulse is

$J=ma\Delta t$

The acceleration can be rewritten as rate of change of velocity:

$a=\frac{\Delta v}{\Delta t}$

So the impulse becomes

$J=m\frac{\Delta v}{\Delta t}\Delta t = m\Delta v$

So, the impulse is equal to the change in momentum: and since in the two cases the change in momentum is the same, the impulse is the same as well.

The force in the collision is related to the impulse by

$J=F\Delta t$

where

J is the impulse

F is the force

$\Delta t$ is the duration of the collision

The equation can be rewritten as

$F=\frac{J}{\Delta t}$

In the two situations described in the problem (A and B), we already said that the impulse is the same (because the change in momentum is the same). However, in case A (padded wall) the time $\Delta t$ is longer, while in case B (unpadded wall) the time $\Delta t$ is shorter: since the force F is inversely proportional to the duration of the collision, this means that in case B the student will experience a greatest force compared to case A.

Learn more about impulse:

brainly.com/question/9484203

#LearnwithBrainly

3 0

4 years ago

Which element's atoms have the greatest average number of neutrons ?

Mkey [24]

I am pretty sure this is uranium. it has 140 neutrons.

6 0

4 years ago

Read 2 more answers

A 0.5 kg ball falls from a building that is 50 meters high. How much kinetic energy will it