Chapter 3: Forces
Date:____________
Section 1.2: Types of Friction - Notes
Learning Goals:
Describe the four different types of friction.
Observe the effects of air resistance on falling objects.
Friction:
Friction: a force that _________________ motion between two surfaces that are touching each other.
o
Why does this happen?
_________________________ form when microscopic dips
and bumps that occur on a surface, no matter how smooth
it may seem, come into contact with another surface.
The greater the force pushing the two surfaces together,
the stronger the microwelds will be, which causes greater
friction. For an object to __________________, the force
must be strong enough to overcome the microwelds.
Types of Friction:
There are 4 main types of friction:
o
o
o
o
______________________________: Occurs between two surfaces that are touching, but not moving
past each other.
o
The object will _______________________.
______________________________: Force that opposes the motion of two surfaces sliding past each
other.
______________________________: Friction between the rolling object and the surface it rolls on.
______________________________: Occurs when a solid object is in contact with a fluid (a gas or
liquid) and a force is applied to either the object or to the fluid
Coefficient of Friction:
Number which represents the ____________________________ between two surfaces.
o
Ranges from _____________
The higher the coefficient, the _____________________________________ between the two surfaces
f=
o
f=
o
Fdrag = the force it takes to ______________________________ in its normal direction of travel
o
Fgravity = the _____________________ of the same object in the same units as the drag force
Practice:
o A book has a weight of 5 N. It takes 3 N of force to drag the book across the surface of a
sidewalk. What is the coefficient of friction?