A 60 kg body is pushed with just enough force to start it moving across a floor and the same force continues to act afterwards. The coefficient of static friction and sliding friction are 0.5 and 0.4 respectively. The acceleration of the body is

Options

A. `1 ms^(-2)`
B. `3.9 ms^(-2)`
C. `4.9 ms^(-2)`
D. `6 ms^(-2)`

Answer

A

Explanation

(a) Kinetic friction `-mu_(k)R=mu_(k) mg=0.4xx60xx10=240N`
and the limiting friction `=mu_(s)R=mu_(s) mg=0.5xx60xx10=300N`
So, the force applied on the body is 300N and if the body is moving afterwards with the same force, then
Net accelerating force =Applied force- Kinetic force
`ma=300-240`
`a=(60)/(m)=(60)/(60)=1 ms^(-1)`