Question

A block of mass 1 kg is pushed up a surface inclined to horizontal at an angle of $30 ^ { \circ }$ 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 $\mathrm { g } = 10 \mathrm {~ms} ^ { - 2 }$)

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

Answer 1

Answer: (B)

50 J

Answer 2

The various forces acting on the block are as shown in the figure.

Here, $\mathrm { m } = 1 \mathrm {~kg} , \theta = 30 ^ { \circ } , \mathrm { F } = 10 \mathrm {~N}$

$\mu = 0.1 , d = 10 \mathrm {~m}$

Work done against gravity is