Phys Static Friction 1

Phys Static Friction 1

by Darrin Shrontz

Poll

Friction depends on what (2 answers):

• how tightly pressed together they are

• the type of material

• the magnetic field present

• the electric capacity of the substrate

• the reactivity of the metals

Multiple Select

Friction depends on what (2 answers):

• how tightly pressed together they are

• the type of material

• the magnetic field present

• the electric capacity of the substrate

• the reactivity of the metals

Poll

How does rubber on concrete and ice on ice compare in terms of static friction coefficient?

• rubber on concreteis much greater

• ice is much greater than rubber on concrete

• ice on concrete is much greater

• these dont compare at all

• they are equal in terms of coefficient

Multiple Choice

How does rubber on concrete and ice on ice compare in terms of static friction coefficient?

• rubber on concreteis much greater

• ice is much greater than rubber on concrete

• ice on concrete is much greater

• these dont compare at all

• they are equal in terms of coefficient

Poll

what is a good definition of static friction?

• none of these

• charges objects with electrical energy

• keeps motion from starting

• starts motion forces

Multiple Choice

what is a good definition of static friction?

• none of these

• charges objects with electrical energy

• keeps motion from starting

• starts motion forces

Multiple Choice

Which of the following is not a type of friction

• Static
• Liquid
• Rolling
• Velcro

Multiple Choice

The person does not fall because of which type of friction?

• Rolling
• Liquid
• Static
• Sliding

Multiple Choice

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

• True

• False

Multiple Choice

What type of friction is not moving?

• static
• sliding
• fluid
• rolling

Multiple Choice

Which of the following is an example of friction that is helpful?

• Brakes used on a bike
• Tires from a car on the road
• Tread on the bottom of your shoes
• All are examples that are helpful

Multiple Choice

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

• The marble’s speed would decrease.
• The marble’s speed would increase.
• The marble would stop immediately. 
• The marble would remain at constant speed.

Multiple Choice

Rougher surfaces have ...

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

Multiple Choice

F_N=100N, F_f=20N

• μ=5.0

• μ=0.2

• μ=1.2

• μ=0.1

Multiple Choice

What direction does friction act relative to motion?

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