A particle starts its motion from rest under the action of a constant force. If the distance covered in first `10 s` is `s_1` and the covered in the first `20 s` is `s_2`, then.

Options

A. `S_(2) = S_(1)`
B. `S_(2) = 2 S_(1)`
C. ` S_(2) = 3S_(1)`
D. `S_(2) = 4 S_(1)`

Answer

D

Explanation

Let a be the uniform acceleration of the particle. Distance covered in first 10 s is
`S_(1) = ut + (1)/(2) at^(2) = (1)/(2) a (10) ^(2) ( as u = 0)`
and that covered in first 20 s is
`S_(2) = (1)/(2) a (20) ^(2) = (1)/(2) a (400) = 4 (1)/(4) a (10) ^(2) = 4 S_(1)`