Question

A body is dropped from rest at a height of 150 m and simultaneously, another body
is dropped from rest from a point 100m above the ground. What is the difference
between heights after they have fallen for 1) 3 Seconds 2) 5 Seconds. Consider that
the body on reaching ground remains there and acceleration due to gravity be
10m/s2​

Answer 1

Explanation:

Initial difference in height =(150−100)m=50m

We know that, by second equation of kinematics, s=ut+

2

1

at

2

considering g=10m/s

Distance travelled by first body in 2s=h1=0+(

2

1

)g(2)

2

=2g=2×10=20m

Distance travelled by another body in 2s=h2=0+(

2

1

)g(2)

2

=2g=2×10=20m

After 2s, height at which the first body will be =h

1

=150−20=130m

After 2s, height at which the second body will be =h

2

=100−20=80m

Thus, after 2 s, difference in height =(130−80)

=50m=initial difference in height

Thus, difference in height does not vary with time. So the answer is zero.