A block of mass 1 kg is pushed up a surface inclined to horizontal at an angle of `30^@` by a force of 10 N parallel to the inclined surface as shown in the figure.
The coefficient of friction between block and the incline is 0.1. If the block is pushed up by 10 m along the incline, then the work against gravity is (Take `g=10 m s^(-2 )`)

Options

A. 10 J
B. 50 J
C. 100 J
D. 150 J

Answer

B

Explanation

The various forces acting on the block are as shown in the figure
Here, m= 1 kg, `theta=30^@`, F=10 N
`mu= 0.1`, d=10 m
Work done against gravity is
`W_g=mgd sin theta`
`=(1 kg)xx(10 m s^(-2))xx 10 xx sin30^@ m=50 J`