Question

a body covers 100 cm in first 2 seconds and 128 in next 2 seconds moving with constant speed acceleration .velocity of the body at the end of 9 sec is?

Answer 1

Answer:

Let u is initial velocity at time t=0 s. Let a be uniform acceleration .

For motion in first 2 s, we have 20=2u+(1/2)a(4) or u+a=10……………(1)

We have used the equation s=ut+(1/2)at^2.

Now for motion in 4s from start,we have 80=4u+(1/2)a(16)=4u+8a or u+2a=20…………..(2)

Solving (1) and (2) for u and a we get

a=10m/s^2 and u=0 m/s.

Now distance in 8s from start.

s=(1/2)(10)(64)==320m.

Therefoe, the distance in 4 seconds after first 4 seconds is 320–80=240 m.