HW3.3 Friction

Friction is a force that acts in an ___________ direction of movement.

• similar
• opposite
• parallel
• west

How can friction be reduced?

• reduce the force acting between the 2 surfaces
• reduce the roughness of the 2 surfaces coming in contact
• use wax, grease or oil
• all of the above are ways of reducing friction

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

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

 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

An 19.6N force pushes on a 4.0kg box horizontally on a table and accelerates the box at 1m/s². What is the coefficient of friction between the box and the table?

Round to ONE decimal place.

Do NOT write units.

Mathematical Equivalence

ON

What is the force of friction between a block of wood that weighs 800 N and the ground if μ = .15?

• 120 N

• 200 N

• 150 N

• 180 N

Smooth surfaces have ...

• greater friction

• less friction

• the same level of friction

F_N=150N, F_f=30N

• μ=5.0

• μ=0.2

• μ=1.2

• μ=0.1