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# Forces and Motion help?? watch

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1. im stuck on this question...the book sais the answer = 1.5m but refuses to tell me how it got that answer....i make it 15m anyone able to help?

A railw wagon moving at a speed of 2ms-1 on a level track reached a steady incline, which slowed it down in 15s and caused it to reverse ...calculate the distance moved up the incline?

Im also stuck on this question if anyone could help i would also be greatfull.

An astronaut on the moon threw and object 4m vertically upwards and caught it gain 4.5s later. calculate the acceleration due to gravity on the moon?....

Cheers..your help would be greatly appreciated
2. An astronaut on the moon threw and object 4m vertically upwards and caught it gain 4.5s later. calculate the acceleration due to gravity on the moon?....
Use the formula h=1/2*g* t2
3. A railw wagon moving at a speed of 2ms-1 on a level track reached a steady incline, which slowed it down in 15s and caused it to reverse ...calculate the distance moved up the incline?
Could you write that again?
4. Cheers for ur help ....but im still stuck

(Original post by Neo~)
Could you write that again?
im afraid not ...with the exception of the wrail typo thats the exact phrasing of the book.

(Original post by Neo~)
Use the formula h=1/2*g* t2
im assuming by h u mean distance...? and if so then it doesnt work/i screwed it up. as

s=1/2gt^2 -----> 2s = gt^2 -----> 2s/t^2 = g ---> 2 times 8/4.5^2

which gives an awnser of 0.79ms-2 ...it isnt the gravitation field strengh of the moon..... The book gives it as 1.6 ms-2. im even more confused now as that answer is preety much dead on half of the correct awnser?? any further help??
5. 2 times 8/4.5^2
actually it 2 times 4/4.5^2...which would give 0.4...

are you sure you're copying down the question right? or maybe you're looking at the wrong answer?

For the first answer, I seem to be getting 15 as well.
6. I'm getting 0.8ms-2. Maybe your book's wrong? Whats it called?
7. OK I did these sums properly on paper & I found out your books right:

t is 2.25 (half of 4.5)
so [4/2.25^2]*2
=1.6ms-2

As for the first one, I get 15m too.
[0-2]-15 = 0.133ms-2
v^2-u^2/2*0.133= 15m
8. (Original post by Neo~)
OK I did these sums properly on paper & I found out your books right:

t is 2.25 (half of 4.5)
so [4/2.25^2]*2
=1.6ms-2

As for the first one, I get 15m too.
[0-2]-15 = 0.133ms-2
v^2-u^2/2*0.133= 15m
Cheers. that questions being buggin me for ahwile....as for the second one im going to guess that the books wrong....in general the books practice questions are really really poor...
9. (Original post by Omer101)
Cheers. that questions being buggin me for ahwile....as for the second one im going to guess that the books wrong....in general the books practice questions are really really poor...
what board are you with?
10. (Original post by Omer101)
Cheers. that questions being buggin me for ahwile....as for the second one im going to guess that the books wrong....in general the books practice questions are really really poor...
Probably a misprint

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