Force Problems 1. A block is pushed across a horizontal surface by the force shown. If the coefficient of kinetic friction between the block and the surface is 0.30, F = 20 N, ɵ = 30°, and m = 3.0 kg, what is the

magnitude of the acceleration of the block?

2. A person pushes a 22 kg lawn mower at a constant speed with a force of 91 N directed along the handle, which is 63° above the horizontal, as shown.

a. Draw the force diagram of the lawn mower.
b. Determine the horizontal resistive force (Kinetic Friction) on the lawn mower. c. Determine the normal force from the ground
3. A child pulls a 15.0 kg sled containing a 5.0 kg dog along a straight path on a horizontal surface. He exerts a force of 55 N on the sled at an angle of 20° above the horizontal, as shown.

a. Draw and label a force diagram of the sled-dog system as it is pulled.
b. Calculate the normal force of the surface on the system
c. If the coefficient of kinetic friction between the sled and the surface is 0.18, what is the acceleration of the sled?
4. A box is given a sudden push. The box then slides on a flat surface and then up a ramp. The box then stops for a moment and then slides down the ramp at a constant speed. Draw the force diagrams AND indicate the direction of the acceleration when:
a. The box is being pushed
b. The box is sliding on a flat surface
c. The box is sliding up the ramp
d. The box is sliding down the ramp (at constant speed)