Question

1. For a huge luxury liner to move with constant velocity, its engines need to supply a forward thrust of 6.75  10⁵ N. What is the magnitude of the resistive force exerted by the water (in N) on the cruise ship?

2.

You are helping your friend move a new refrigerator into his kitchen. You apply a horizontal force of 272 N in the negative x direction to try and move the 62 kg refrigerator. The coefficient of static friction is 0.64.

(a) How much static frictional force does the floor exert on the refrigerator? Give both magnitude (in N) and direction.

magnitude & direction

(b) What maximum force (in N) do you need to apply before the refrigerator starts to move?

3. A flatbed truck is supported by its four drive wheels, and is moving with an acceleration of 6.6 m/s². For what value of the coefficient of static friction between the truck bed and a cabinet will the cabinet slip along the bed surface?

μ_s <

4. (a) What is the maximum frictional force (in N) in the knee joint of a person who supports 59.0 kg of her mass on that knee if the coefficient of static friction is 0.016?

(b) During strenuous exercise, it is possible to exert forces to the joints easily ten times greater than the weight being supported. What is the maximum force of friction (in N) under such conditions? The frictional forces in joints are relatively small in all circumstances except when the joints deteriorate, such as from injury or arthritis. Increased frictional forces can cause further damage and pain. Assume that the coefficient of kinetic friction in the joint is 0.015.

5. A 6 kg block slides down a ramp which is at an incline of 40°. If the frictional force is 5.40 N, what is the coefficient of friction? Assume g = 10 m/s².

At what incline (measured in degrees) will the box slide at a constant velocity?

Answer 1