A particle starts from rest with constant acceleration. It travels a distance `x` in the first `10 s` and a distance `y` in the next `20 s.` The relation between `x` and `y` is-

(A) `y = x`
(B) `y = 2x`
(C) `y = 8x`
(D) `y = 4x`

Options

A. y =x
B. y = 2x
C. y = 8x
D. y = 4x

Answer

C

Explanation

We know s = `ut + (1)/(2) at^(2), ` u=0
When t = 10 s, s = x then x = `(1)/(2) xxaxx100 = 50 a`
When t = 10+20 = 30 s, s =s+y,
then x+y=`(1)/(2)xxaxx900 = 450a`
`:. " " y = (x+y)-x = 450a-50a=400a=8x`