# Physics multiple choice mass, acceleration, velocity based question

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This is the question:

Two unpowered toy cars, P and Q, are released from rest from X and travel down the track to Y. Car P has twice the mass of car Q. There is negligible friction. What quantity is the same for car P and car Q?

a) the gravitational potential at X

b) the accelerating force at X

c) the velocity when they arrive at Y

d) the momentum when they arrive at Y

I initially thought that the answer was b (the accelerating force at X) but then found out that the answer was c (the velocity). Could someone please explain how the answer is c because I'm not sure how to explain it. Thanks.

Two unpowered toy cars, P and Q, are released from rest from X and travel down the track to Y. Car P has twice the mass of car Q. There is negligible friction. What quantity is the same for car P and car Q?

a) the gravitational potential at X

b) the accelerating force at X

c) the velocity when they arrive at Y

d) the momentum when they arrive at Y

I initially thought that the answer was b (the accelerating force at X) but then found out that the answer was c (the velocity). Could someone please explain how the answer is c because I'm not sure how to explain it. Thanks.

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#2

b says accelerating force, which means resultant force = mg sin theta

So it depends on mass

Speed does not depend on mass

So it depends on mass

Speed does not depend on mass

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(Original post by

b says accelerating force, which means resultant force = mg sin theta

So it depends on mass

Speed does not depend on mass

**Aung**)b says accelerating force, which means resultant force = mg sin theta

So it depends on mass

Speed does not depend on mass

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#5

(Original post by

ceg250 . There is still an issue with this question.

Is the answer a) copied correctly?

**Stonebridge**)ceg250 . There is still an issue with this question.

Is the answer a) copied correctly?

If it says gravitational potential, a is also correct.

Because gravitational potential only depends on mass of Earth and distance from centre.

If it says gravitational potential energy, it also depends on mass of car.

G.P = -GM/r

G.P.E = -GMm/r

But even if the question is copied correctly, it is more likely to be c.

Because although GPE is taught since year9/year10, GP is only taught in year13.

So if this is an AS question, we don't need to consider about it.

Last edited by Aung; 5 months ago

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#6

If more than one answer is allowed, then a) is certainly also correct.

I suspect, though, that only one correct answer is allowed, which means we have to conclude that

it is a typo and should have been 'gravitational potential energy'

it's a really poor physics question that somehow got through the shredding process.

I suspect, though, that only one correct answer is allowed, which means we have to conclude that

**either**it is a typo and should have been 'gravitational potential energy'

**or**it's a really poor physics question that somehow got through the shredding process.

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(Original post by

If more than one answer is allowed, then a) is certainly also correct.

I suspect, though, that only one correct answer is allowed, which means we have to conclude that

it is a typo and should have been 'gravitational potential energy'

it's a really poor physics question that somehow got through the shredding process.

**Stonebridge**)If more than one answer is allowed, then a) is certainly also correct.

I suspect, though, that only one correct answer is allowed, which means we have to conclude that

**either**it is a typo and should have been 'gravitational potential energy'

**or**it's a really poor physics question that somehow got through the shredding process.

Yeah just realised it was a typo it was supposed to be gravitational potential energy. Sorry about that. Thanks for all the help.

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