Net force and coefficient of friction

The amount of friction depends on the normal force of the objects pressing together.

• True

• False

What type of friction is not moving?

• static
• sliding
• fluid
• rolling

How would the absence of friction affect a marble traveling on a long, straight path?

• The marble’s velocity would decrease.

• The marble’s would accelerate.

• The marble would stop immediately.

• The marble would remain at constant velocity.

Tags

NGSS.HS-PS2-1

Rougher surfaces have ...

• greater friction
• less friction
• the same level of friction

F_N=100N, F_f=20N

• μ=5.0

• μ=0.2

• μ=1.2

• μ=0.1

Tags

NGSS.HS-PS2-1

In what direction does friction act, relative to motion?

• in the same direction

• in the opposite direction

• need more information

• depends on the force

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 0.54. What is the weight of the box?

• 81 N

• 18 N

• 98 N

• 74 N

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