A block of mass m=10 kg is resting on a rough surface `mu_(S)=0.4, mu_(k)=0.3`. It is pulled by a force F=30 N at an angles of `53^(@)` above horizontal. What is the work done by friction till t=10 sec

Options

A. zero
B. `-9000 J`
C. `-6000 J`
D. `-2000 J`

Answer

A

Explanation

`30 sin 53^(@) +N=100`
`N=100-30xx4/5 =76`
`f_(max) =muN =0.4xx76`
`f_("applied")=30 cos 53^(@) =3 xx3/5 =18 N`
`rArr` no motion