Question

A block of mass M is resting on an inclined plane as shown in the figure. The inclination of the plane to the horizontal is gradually increased. It is found that when the angle of inclination is q the block just begins to slide down the plane. What is the minimum force F applied parallel to the plane that would just make the block move up the plane?

• A. Mg sin q
• B. Mg cosq
• C. 2Mg cosq
• D. 2Mg sin q

Answer 1

Answer: (D)

2Mg sin q

Answer 2

Initially in just sliding condition F_t = Mg sinq

When block is moving in the upward direction then frictional force will act in the downward direction.