Inclined Planes

What direction does friction act relative to motion?

• in the same direction
• in the opposite direction 
• need more information
• depends on the force

Which of the following is the best expression for the Normal Force?

• F_N = mg cos(ϴ)

• F_N = mg sin(ϴ)

• F_N = mg sin(180-ϴ)

• F_N = mg cos(90-ϴ)

A box weighing 46 newtons rests on an incline that makes an angle of 25° with the horizontal. What is the magnitude of the component of the box’s weight perpendicular to the incline?

• 19N
• 21N
• 42N
• 26N

An 8.0-newton block is accelerating down a frictionless ramp inclined at 15° to the horizontal. What is the magnitude of the net force causing the block’s acceleration (parallel to the ramp)?

• 0N

• 2.1N

• 7.7N

• 8.0N

A cart rolls down an inclined plane with constant speed as shown in the diagram below. Which arrow represents the direction of frictional force?

• A
• B
• C
• D

A 10.-newton block is sliding down a 30-degree incline at a constant speed. What is the force of friction?

• 5N
• 4.9N
• 10N
• 98N

If there is no friction, then the acceleration would be equal to

• mg

• sin(θ)mg

• g

• sin(θ)g

a 43 kg box is on a 32 degree inclined plane with a friction coefficient of .23 What is the F_net