# A particle moves in a straight line with a constant acceleration. It changes its velocity from…

Q: A particle moves in a straight line with a constant acceleration. It changes its velocity from 10 ms–1 to 20 ms–1 while passing through a distance 135 m in t sec. The value of t is

(a) 10

(b) 1.8

(c) 12

(d) 9

Ans: (d)
Sol:
Acceleration, a = (20-10)/t = 10/t
Using ,
$\displaystyle v^2 = u^2 + 2 a s$

$\displaystyle 20^2 = 10^2 + 2 (10/t) \times 135$