15. (a) How long will a stone take to fall to the ground
from the top of a building 80 m high and (b) what
will be the velocity of the stone on reaching the
ground ? (Take g = 10 m s2)
Answers
Answered by
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GIVEN:- Distance=height of the tower=s=80m
Acceleration=g=10m/sec^2
Initial velocity=u=0m/s. (because the stone is falling from rest under free fall)
TO FIND:-a)time =t, b)final velocity=v
a)
To find t we have to use this formula that s=ut+1/2gt^2
80=0*t+1/2*10*(t)^2
80=0+1/2*10t^2
80=0+5t^2
5t^2=80
t^2=80/5
t^2=16
t=√16
t=4sec
b)
To find v we have to use this formula g=(v-u)/t
10=(v-0)/4
10*4=v
v=40m/sec
HOPE THIS WILL HELP YOU
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