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# How do you do this very basic AS mechanics question? (physics) watch

1. A ball is kicked off a flat roof with a horizontal velocity of 12ms^-1. How would you:
a) calculate the horizontal distance travelled after it has fallen 15m
when i try to resolve in the x plane, i find that i dont know the acceleration or time? is there some sort of formula im unaware of?
b) the resultant velocity after 1.9s
the word resultant velocity put me off. after getting the answer to part a, what do i do? :s do i just use a suvat formula or what?

THANKS
2. Horizontal component has an acceleration of 0 if that helps.
3. (Original post by xSkyFire)
Horizontal component has an acceleration of 0 if that helps.
oh snap! then after i work out what the time is, what's the next stage? this whole vertical and horizontal component bs has me confused.
4. (Original post by dumb maths student)
oh snap! then after i work out what the time is, what's the next stage? this whole vertical and horizontal component bs has me confused.
A ball is kicked off a flat roof with a horizontal velocity of 12ms^-1. How would you:
a) calculate the horizontal distance travelled after it has fallen 15m
when i try to resolve in the x plane, i find that i dont know the acceleration or time? is there some sort of formula im unaware of?
b) the resultant velocity after 1.9s
the word resultant velocity put me off. after getting the answer to part a, what do i do? :s do i just use a suvat formula or what?

well the vertical component is -1/2at^2 since sin here is 0
so 15 = 1/2at^2 with -9.8 equal to a

you can get t from that, the plug that into s = ut + 0 for the other one

then for the resultant it's just pythagoras @ 1.9s

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