Friction

Front

Static Friction is present only when an object is at rest.

Back

True.

Front

What is the magnitude of F_N for a block pulled along a rough level surface at constant speed?

Back

mg

Front

A 27.6 kg block is pulled along a rough level surface at constant velocity by the force P. The coefficient of kinetic friction is 0.30. What is the strength of P?

Back

81 N

Front

A 2.0-N force acts horizontally on a 10-N block that is initially at rest on a horizontal surface. The coefficient of static friction between the block and the surface is 0.50. What is the magnitude of the frictional force that acts on the block?

Back

2 N

Front

A 2.0-N rock slides on a frictionless inclined plane. Which one of the following statements is true concerning the normal force that the plane exerts on the rock?

Back

The normal force is less than 2 N, but greater than 0 N

Front

Under what condition(s) will an object be in equilibrium? (Hint: An object can be in static equilibrium or dynamic equilibrium).

Back

If the object is either at rest or moving with constant velocity, it is in equilibrium.

Front

A block of mass M is held motionless on a frictionless inclined plane by means of a string attached to a vertical wall. What is the magnitude of the tension in the string?

Back

Front

Back

3.70 N

Front

A 10-kg block is pushed against a vertical wall by a horizontal force of 100 N. The coefficient of static friction, 𝜇_s, between the block and the wall is 0.60; and the coefficient of kinetic friction, 𝜇_k, is 0.40. Which statement is true if the block is initially at rest? Options: The block will slide down the wall because the force of static friction can be no larger than 60 N. The block will slide down the wall because the coefficient of kinetic friction is less than the coefficient of static friction. The block will remain at rest because the coefficient of static friction is greater than the coefficient of kinetic friction. The total force exerted on the block by the wall is directed horizontally.

Back

The block will slide down the wall because the force of static friction can be no larger than 60 N.

Front

A child (m=30.0 kg) slides down a slide at a 42° angle with a coefficient of kinetic friction of 0.20. What is the magnitude of her acceleration?

Back

5.1 m/s²