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# help with gcse physics question Watch

question 1) a van is parked on a hill .

the breaks fail and the van rolls down the hill .
the resultant force pulling the van down the hill is 2000N.
the van has a mass of 1000kg.
how fast is the van moving 5 seconds after the brakes fail?

5 m/s,
10 m/s,
20 m/s or
40 m/s.

what calculation would you use to find out the correct answer?

question 2) sandy is in a hot air ballon in the sky.
she releases a sandbag which falls a distance of 2m to the ground.
it has a weight of 100n and a mass of 10kg.
if there is no friction, how fast is the sandbag moving when it hits the ground?

6.3 m/s,
20 m/s,
40 m/s or
2000 m/s.

which calculation would you use to find out the correct answer?

2. Are you familiar with the 'SUVAT' equations? More information at the link below, if you aren't. You can use these to solve both questions here, along with Force = mass × acceleration

http://en.wikipedia.org/wiki/Equations_of_motion
3. Question 1) Use F = ma to find a.
Use that to find V using V = U + at

Question 2) You'd use GPE = mgh
Convert all to KE as there's no friction.
Rearrange to find V.
4. (Original post by Illusionary)
Are you familiar with the 'SUVAT' equations? More information at the link below, if you aren't. You can use these to solve both questions here, along with Force = mass × acceleration

http://en.wikipedia.org/wiki/Equations_of_motion
No not. Ive clicked on the link but it doesnt seem to make sense- mind you im still doing Gcse's so maybe thats why.
5. (Original post by nerd1234)
No not. Ive clicked on the link but it doesnt seem to make sense- mind you im still doing Gcse's so maybe thats why.
I'm pretty sure that the equations are on the GCSE syllabus - at least, they were when I did GCSE. Anyway, the equations that you need are v = u + at, then v² = u² + 2as.

Here, v = final speed, u = initial speed, a = acceleration, t = time and s = distance.

Can you see where to go from here?
6. (Original post by WhatamIdoing)
Question 2) You'd use GPE = mgh
Convert all to KE as there's no friction.
Rearrange to find V.
That seems a bit complicated. Couldn't you just use v² = u² + 2as?
7. (Original post by TheGrandmaster)
That seems a bit complicated. Couldn't you just use v² = u² + 2as?
Yeah, but I don't think they do v² = u² + 2as or s =ut +0.5at² at GCSE. I think the only kinematic equation of motion they do at GCSE is v = u +at.

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