Unit 04 Friction, Force and Motion 23-24

What are 2 factors that determine the amount of friction between 2 objects?

• Force and roughness between surfaces
• hills and valleys and how smooth or rough the surface is
• Amount of force and amount of surface the comes in contact
• The force and the weight exerted on the surfaces

Friction is a force that acts in a(n) __________ direction of movement.

• similar

• opposite

• parallel

• north

What type of friction is present when an object is not moving?

• static
• sliding
• fluid
• rolling

An object (10 kg) sits on a horizontal surface. If F_f (s) = 20 N, what is the coefficient of static friction?

• μ = 5.0

• μ = 0.2

• μ = 1.2

• μ = 0.1

 What is the force of friction between a block of ice with a mass 95 kg and the ground if μ_k = 0.12? 

• 65 N
• 226 N
• 175 N
• 114 N

It takes a minimum of 44 N of force to move a toy box (8.6 kg).  What is the coefficient of static friction?

• 0.78
• 0.51
• 0.78 N
• 0.58 N

Tags

NGSS.HS-PS2-1

Which would NOT be a way of reducing friction?

• making the surfaces smoother
• using lubricants such as waxes, oils, or grease
• changing from sliding friction to rolling friction using ball bearings
• Using kitty litter on snow and ice to help your car gain traction

If the net force in the horizontal direction of an object is zero, what can we say about its horizontal acceleration?

• it is positive

• it is negative

• it is zero

• not enough information is given

Tags

NGSS.HS-PS2-1

If the net force in the horizontal direction of an object is zero, what can we say about its horizontal friction?

• It is double the mass

• It is equal in magnitude to the applied force.

• It is zero

• It is less than the applied force.

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