Question

A stone is dropped from a balloon rising upwards with velocity of 16 m/s. The stone reaches the ground in 4s. Calculate the height of the balloon when stone was dropped.

Answer 1

According to the question:

u=16m/s, v=0m/s, a=g=-10m/s^2

By formula v^2=u^2+2as

0=(16)^2+2(-10)s
0=256-20s
-256=-20s
s=-256/-20
=12.8

Let x be the initial height of the balloon

Using formula t to reach ground when falling freely=√2h/g

√2(x+12.8)/10=4
2x+25.6/10=16
2x+25.6=160
2x=160-25.6
2x=134.4
x=134.4/2
=67.2 metres

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