friction and 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

Tags

NGSS.3-PS2-1

 What is the force of friction between a block of ice that weighs 950 N and the ground if μ = .12? 

• 65 N
• 226 N
• 175 N
• 114 N

Tags

NGSS.MS-PS2-2

What is the coefficient of static friction if it takes 44 N of force to move a box that weighs 86 N? 

• 0.78
• 0.51
• 0.78 N
• 0.58 N

Tags

NGSS.HS-PS2-1

A box takes 40 N to start moving when the coefficient of static friction is .54. What is the weight of the box? 

• 81 N
• 18 N
• 98 N
• 74 N

Tags

NGSS.HS-PS2-1

What are the units on the force due to friction?

• none
• Newtons
• meters
• kilograms

Tags

NGSS.HS-PS2-1

F_N=100N, F_f=20N

• μ=5.0

• μ=0.2

• μ=1.2

• μ=0.1

Tags

NGSS.HS-PS2-1

When looking at friction problems, if the net force in the x-direction on an object is zero, what can we say about its acceleration?

• it is positive

• it is negative

• it is zero

• not enough information is given

Tags

NGSS.HS-PS2-1

Normal force is

• Always opposite the weight

• Always parallel and down the incline

• Always perpendicular to the surface

• It depends on the direction of motion

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)

Tags

NGSS.HS-PS2-1

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

Tags

NGSS.HS-PS2-4