Friction

Question 1

Friction - Def

Answer 1

Friction is the force acting parallel between two contacting surfaces that tend to rub ot slide past each other

Question 2

Does friction require movement?

Answer 2

No!

Question 3

Friction is…

Answer 3

• FUN!
• N is related to the reaction force and is always perpendicular to the surface. Anytime N becomes less, friction becomes less. Ex: Driving down a hill you accelerate due to lack of friction

Question 4

Answer 4

Friction magnitude is VARIABLE
- Until sliding occurs, friction magnitude = motive force “limiting friction”
- Once sliding occurs, friction magnitude decreases, “sliding friciton”

Question 5

Factors affecting Friction

Answer 5

• Materials of contacting surfaces
• Soles of shoes, cartilage vs fibro cartilage, crutch tips and floor
• Cleats vs Tennis shoes on turf vs on tile

Question 6

Changing Friction down a hill

Answer 6

N is force that is equal to the parallel force. As the hill gets steeper the N gets smaller therefore less overall force. Leads to you speeding up in a car.

Question 7

Why is cartilage irreplaceable?

Answer 7

Nothing manmade that is as slippery. Joint replacements must be replaced after 10-20 years due to friction wearing it out