A boy standing near the edge of a cliff 125 m above a river throw a stone downward with a speed of 10 ms. find<br /> A. with what speed will the stone hit water and <br />B. how long will it take to descend
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a)
s=125m u=10ms v=? a=-9.81m/s^2
v^2=u^2+2as (a is in positive in this case)
v^2=100+2(9.81)(125)
v^2=255.25
v=![\sqrt[2]{255.25}](https://tex.z-dn.net/?f=+%5Csqrt%5B2%5D%7B255.25%7D+ "\sqrt[2]{255.25}")
v=50.52m/s moving downward
b)v=u+at
50.52=10+(9.81)t
9.81t=40.52
t=4.13s
s=125m u=10ms v=? a=-9.81m/s^2
v^2=u^2+2as (a is in positive in this case)
v^2=100+2(9.81)(125)
v^2=255.25
v=
v=50.52m/s moving downward
b)v=u+at
50.52=10+(9.81)t
9.81t=40.52
t=4.13s
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