Question

The initial velocity of a body moving on a rough horizontal surface having coefficient of friction 0.5 is 15 m/s. Find the time after which it will come to rest . [Take g = $10m/s^2$ ]

• A. 1.5 s
• B. 3 s
• C. 6 s
• D. 7 s

Answer 1

The correct option is B 3 s

Due to friction, the body face a retardation of $a=\mu g$ [$\mu$ : coefficient of friction]

also $u=15m/s$ and $v=0$ (as it comes to rest)

From kinematics,

$v=u+at$ which means:

$\Rightarrow 0=15-\mu gt\Rightarrow t=\frac{15}{mg}=\frac{15}{0.5\times 10}=35$ Ans