Question

A particle is moving in a straight line with a constant acceleration. It changes its velocity from 10 $\frac{m}{s}$ to 20$\frac{m}{s}$ in ‘t’ second. If the displacement of the particle during this interval is 135 m, the value of ‘t’ is

• A. 10 seconds
• B. 1.8 seconds
• C. 12 seconds
• D. 9 seconds

Answer 1

The correct option is D

9 seconds

Average velocity = $\frac{(10+20)}{2}$ = $15\frac{m}{s}$
Displacement = Average velocity x Time
135 = $15\times t$
t = $\frac{135}{15}$ = 9 seconds.