Question

To understand kinetic and static friction.

A block of mass m lies on a horizontal table. The coefficient of static friction between the block and the table is μs. The coefficient of kinetic friction isμk, with μk<μs.

Part B

Suppose you want to move the block, but you want to push it with the least force possible to get it moving. With what force F must you be pushing the block just before the block begins to move?

Part C

Suppose you push horizontally with half the force needed to just make the block move. What is the magnitude of the friction force?

Express your answer in terms of some or all of the variables μs, μk, and m, as well as the acceleration due to gravity g.

Part D

Suppose you push horizontally with precisely enough force to make the block start to move, and you continue to apply the same amount of force even after it starts moving. Find the acceleration a of the block after it begins to move.

Express your answer in terms of some or all of the variables μs, μk, and m, as well as the acceleration due to gravity g.

please verify the answer before you sent it to me thank you

Answer 1

(B) F_min = f_s = mu_s N = mu_s mg (sigma F_y = 0 N - mg = 0 N = mg) (C) The force less than force need to just move is equal to the kinetic friction force. f_k = F/2 = mu_s mg/2 (D) the net force on the block is, F_net = F - f_k ma = mu_s mg - mu_s mg/2 a = mu_s g/2