Chapter 5: Force & Motion
A push or pull on an object
Force is a vector; it has both magnitude and a direction
Force requires an agent; something has to be doing the pushing or pulling
Force is either a contact or long range force
A Short Catalog of Forces:
“Gravity is absolutely down.
Normal force is perpendicular.
Frictional force is very peculiar.
An object stays because of static friction.
Kinetic friction is always opposite the motion.”
o Gravity- a long-range force; object experiences the force without any contact
o Spring force- a contact force; object experiences force only with a contact
A compressed spring exerts a pushing force on an object
A stretched string exerts a pulling force on an object
o Tension- a contact force; object experiences the force through the contact with the
string (pulling force)
Ex: rope exerts a tension force on the sled
o Normal force- a contact force; an object experiences force through the contact with
a surface (pushing); always perpendicular to the surface
The surface pushes outward against the bottom of the frog; the push is