Question

A stone falls freely from rest and the total distance covered by it in last second of its motion equals the distance covered by it in the first three seconds of its motion. The stone remains in the air for​

Answer 1

Answer

s =ut + 0.5gt

2

_________1

In first 3sec, let it covers distance "d" m.

d=0.5g(3)

2

=4.5g

This distance is same as distance traveled in last second

So, according to formula,

S

n

=u+0.5a(2n−1)

4.5g=0.5g(2n−1)

Here, u=0 and n is number of seconds for which stone is in air.

∴n=5 sec

Substituting in eqn 1,

S= 122.5m