Question

A body covers a displacement of 20 m in the 7th second of its motion and 24 m in 9th second of its motion,
then its displacement in the 15th second will be
(A) 28 m
(B) 32 m
(C) 36 m
(D) 40 m​

Answer 1

Answer:

Assuming the body is under uniform acceleration, let the velocity at 7th and 9th second be v7 and v9.

V7= 20 m/s and V9= 24 m/s

Rate of change of velocity=(V9-V7) / Change in time

This implies Uniform acceleration = (24–20)/2

Thus acceleration a=2 m/s2

Now, distance travelled in 15th second is Veloctiy at t=15 s. Let's call it V15;

According the well known formula:

V15= U7 + a*time = 20+(2*8) = 36 m/s

Thus the body will travel 36m in the 15th second.