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 coefficients of static and sliding friction are 0.5 and 0.4 respectively. The acceleration of the body is

Options

A. `6 m//sec^2`
B. `4.9 m//sec^2`
C. `3.92 m//sec^2`
D. `0.98 m//sec^2`

Answer

D

Explanation

`F_r=mu N`
`F=0.5 xx 60 xx 9.8=294N ("static")`
`F=0.4 xx 60 xx 9.8=235.2 N ("kinetic")`
`a=F/m=(58.8)/60=0.98 m//s^2`