expression for the magnitude of the frictional force on the block if it is moving at constant speed? (A) 𝜇𝑘𝑚𝑔(B) 𝜇𝑘𝐹 cos𝜙(C) 𝜇𝑘(𝐹 sin 𝜙 + 𝑚𝑔)(D) 𝜇𝑘(𝐹 sin 𝜙 − 𝑚𝑔)(E) 𝜇𝑘(𝑚𝑔 − 𝐹 sin𝜙)
4. Two 4 kg blocks hang from a rope that passes over two frictionless pulleys, as shown in the figure above. What is the tension in the horizontal portion of the rope if the blocks are not moving and the rope and the two pulleys have negligible mass?
(E) 80 N 5. A person throws a ball of mass 0.20 kg. The ball starts from rest, accelerates horizontally and uniformly through a distance of 0.90 m, and leaves the person’s hand at 30 m/s. The average horizontal force applied to the ball by the person’shand is