Answer key to the review sheet in the previous post: Here
Tonight's homework: read p.83-86 and p.86#1-7
Today in class we explored friction, the force that opposes sliding motion between two items in contact.
We determined:
-Weight, or force between objects, increases frictional force by making surfaces conform to one another and increases microscopic surface contact, which results in more microwelds and more friction.
-Surface area (on the scale that we can see, not microscopically) has pretty much no effect on friction.
-Surface types have a great effect on friction
-water may increase or decrease friction, depending on the circumstances (wiping dirt off shoes, etc)
-Motion is related to friction!
2 types of friction are related to motion:
Static friction: When 2 surfaces are not moving past one another, the maximum amount of friction between them is labeled as static friction.
Kinetic (sliding) friction: When surfaces slide past one another, kinetic friction is experienced. Kinetic friction is lower than static friction.
Your car's Anti-Lock Brakes (ABS) make use of static friction; they adjust pressure to the brakes many times per second to allow for maximum braking without locking the wheels and causing them to slide. This not only allows you to stop faster, but also to steer your car while you are braking.
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