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Circular Motion
Going in circles means that you are
accelerating
Whenever you
travel in a circle,
you are always
changing
direction.
A net force causes acceleration.
For circles, the net force is given a
special name. It is called a
Centripetal
force
Centripetal means “center-seeking” so
the centripetal force (Fc) is always
directed toward the center of the circle.
Fc
Fc
Fc
**** Remember: The centripetal force is always a
net force
which means it comes from other physical forces.
For example:
Fg= Fc
For a satellite
orbiting the Earth,
the centripetal
force is produced
by gravity.
For a car going around a track
or curve, FRICTION between
the road and tires provides the
centripetal force.
Static
= Fc
friction
Centripetal acceleration
•
•
Since an acceleration is caused by a net
force, then centripetal acceleration is
caused by a centripetal force.
Centripetal acceleration will only cause a
change in direction, not speed
Centripetal acceleration is also
directed toward the center of the circle
ac
ac
ac
Velocity in a circle
• Velocity is always
directed tangent to
the circle
• Velocity is in the
direction of the object
at the instant shown v
v
v
If the net force disappears, the object
cannot travel in circle and travels in a
straight line which is tangent to the circle.
Show cc II chap 26