Question

a body covers 12 m in 2nd second 20 m in 4th second find acceleration and inital velocity

Answer 1

Answer:

Given that the motion is in 1 Dimension and the body doesn't change it's direction (i.e. velocity is in the direction of acceleration), we have:

s=u+a(2t−1)/2

12 = u + a(2*2 - 1)/2

=> 12 = u + 3a/2

=> 2u + 3a = 24

and

20 = u + a(2*4 - 1)/2

20 = u + 7a/2

=> 2u + 7a = 40

From 1 and 2:

a = 4

u = 6

Now, distance covered in 4s after 5th second = Distance covered in 9 seconds - distance covered in 5 seconds

= 6*9 + 1/2 * 4 * 9 * 9 - (6 * 5 + 1/2 * 4 * 5 * 5)

= 54 + 162 - (30 + 50)

= 136 m

Explanation: