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Gravity Mechanics Question; How to work this out? watch

1. A ball is initially at rest. It falls from a height of 4m to the ground. Find
a)The time ot takes to fall to the ground
b)its speed when it hits the ground

a)0.904s
b)8.85ms

please explain how to work this out, my teacher keeps setting homework on things we haven't even done in class (and then she gets pissed when no one's done their homework??) so I'm so baffled please help?

thank you
2. (Original post by BuuTuu)
A ball is initially at rest. It falls from a height of 4m to the ground. Find
a)The time ot takes to fall to the ground
b)its speed when it hits the ground

a)0.904s
b)8.85ms

please explain how to work this out, my teacher keeps setting homework on things we haven't even done in class (and then she gets pissed when no one's done their homework??) so I'm so baffled please help?

thank you
use SUVAT
3. You need (and have) the three bits of info needed .....find them and find an equation of motion to suit
4. So I have s, u and a and I need to find out v and t? right?
s=4m
u=0
v=?
a=9.8ms^2
t=?
5. Just put the numbers into the correct equations...
6. (Original post by BuuTuu)
So I have s, u and a and I need to find out v and t? right?
s=4m
u=0
v=?
a=9.8ms^2
t=?
s=ut + 0.5at^2 ( use to find t)

v^2 = u^2+ 2as ( use to find v)
7. (Original post by dean01234)
s=ut + 0.5at^2 ( use to find t)

v^2 = u^2+ 2as ( use to find v)
Got it, thanks
8. i`d point out to your teacher to teach you how to do these things before she asks you!
9. (Original post by Hasufel)
i`d point out to your teacher to teach you how to do these things before she asks you!
lol, I plan to

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