physics

A 50.0 N box is at rest on a horizontal surface. The coefficient of static friction between the box and the surface is 0.50, and the coefficient of kinetic friction is 0.30. A horizontal 20.0 N force is then exerted on the box. The magnitude of the acceleration of the box is most nearly

0

A box of mass m is on a rough inclined plane that is at an angle θ with the horizontal. A force of magnitude F at an angle Φ with the plane is exerted on the block, as shown above. As the block moves up the plane, there is a frictional force between the box and the plane of magnitude f. What is the magnitude of the net force acting on the box?

F cosΦ - mg sin θ - f

Block A and block B move toward each other on a level frictionless track. Block A has mass mand velocity +v . Block B has mass 2m and velocity -v . The blocks collide, and during the collision the magnitude of the net force exerted on block A is F. What is the magnitude of the net force exerted on block B, and why does it have that value?

F, because the net force is equal to the mutual contact force between the blocks.

The stacks of boxes shown in the figure above are inside an elevator that is moving upward. The masses of the boxes are given in terms of the mass M of the lightest box. Assume the elevator has upward acceleration a, and consider the stack that has two boxes of mass M. What is the magnitude of the force exerted on the top box by the bottom box?

M (a + g)

A person is running on a track. Which of the following forces propels the runner forward?

The force of friction exerted by the ground on the person