Question

The weight of the block in the drawing is 81.9 N. The coefficient of static friction between the block and the vertical wall is 0.430.

(a) What minimum force vector F is required to prevent the block from sliding down the wall? (Hint: The static frictional force exerted on the block is directed upward, parallel to the wall.)


(b) What minimum force is required to start the block moving up the wall? (Hint: The static frictional force is now directed down the wall.)

Answer 1

(a) The minimum force vector F required to prevent the block from sliding down the wall is equal to the force of static friction, which is equal to the coefficient of static friction multiplied by the weight of the block. In this case, the minimum force vector F is:

F = μs * Fg = 0.430 * 81.9 N = 35.4 N

(b) The minimum force required to start the block moving up the wall is the force of kinetic friction which is typically less than the force of static friction. The force of kinetic friction is given by:

F = μk * Fg where μk is the coefficient of kinetic friction.

However, in this question, the coefficient of kinetic friction is not given. So, we can't calculate the minimum force required to start the block moving up the wall.