Question

A body A starts from rest with an acceleration a1 . After 2s , another body starts from rest with acceleration a2 . If they travel equal distance in fifth second after the start of A .Find the ratio a1:a2

Answer 1

For the body ‘A’, the distance travelled in 5th second is,

S5 = 0 + ½ a1 (2n - 1)

=> S5 = 9/2 a1   [n = 5]

For the body ‘B’, the distance travelled in the 5th second after the start of A is actually the distance travelled by the body B in the 3rd second, since, B starts 2 s later.

Therefore,

S3 = 0 + ½ a2 (2n - 1)

=> S3 = 5/2 a2  [n = 3]

Since, the distance travelled are same,

9/2 a1 = 5/2 a2

=> a1 : a2 = 5 : 9