1. Contact Friction Forces:
Force of Static Friction fs m mg
Force of Kinetic Friction v N F fk m mg

2. Coefficients Of Friction Steel on steel 0.74 0.57
Aluminum on steel
Copper on steel
Rubber on concrete
Wood on wood
Glass on glass
Waxed wood on wet snow
Waxed wood on dry snow
Metal on metal (lubricated)
Ice on ice
Teflon on Teflon

3. y N F N mk F q f q m f x mg mg Pulling a block with constant speed
The coefficient
of friction
The normal force
The frictional force
A man drags a 20 kg crate at constant speed across a floor by pulling on a rope inclined at 35 degrees above the horizontal. The tension in the rope is 40 N.
Find the magnitude of the
a) normal force exerted on the crate by the floor.
b) frictional force acting on the crate.
c) coefficient of kinetic friction between the crate and floor.

4. What is the truck’s maximum deceleration ? ms = 0.500
Crate on truck
m = 200 kg
vo= 20 m/s
What is the truck’s maximum
deceleration ?
ms = 0.500
A flatbed truck traveling at 20 m/s is carrying a 200 kg crate of heavy machinery. The coefficient of static friction between the crate and the bed of the truck is The driver applies the brakes and brings the truck to rest as quickly as possible without the crate sliding
Find the
a) magnitude of the trucks acceleration when coming to a stop?
b) time of the acceleration?
c) distance traveled during the acceleration?