Question

A body is sliding down an inclined plane forming an angle ${30}^0$ with the horizontal. If the coefficient of friction is 0.3, its velocity after 3 seconds in $m{s}^{-1}$ is

• A. 7.06
• B. 14.7
• C. 29.4
• D. Zero

Answer 1

Answer: (A)

7.06

Forces acting on the body along the plane is:
$ma=mgsin\theta -\mu mgcos\theta$
$a=g(sin\theta -\mu cos\theta )=9.8(sin{30}^o-0.3(cos{30}^o\left)\right)=2.356m/s^2$
Velocity after 3 seconds $=\left(2.356\right)\left(3\right)=7.06m/s$