Download Notes intro to Uniform Circular Motion

Uniform Circular Motion
Uniform Circular Motion
• Answer the following questions in your lab
group:
– What makes the motion “uniform?”
– What are the measurable variables involved in the
motion?
– How do you measure the speed of the object?
– Is the velocity constant?
– Is there acceleration? ( what are the ways an
object can accelerate? Tricky tricky!)
– What direction is the net force acting on the
object?
• Uniform circular motion is the motion of an
object that is traveling at a constant speed on
a circular path.
• This means:
– Constant radius
– Constant speed
Speed in circular motion
• The formula for speed:
d
s
t
• How do you find the distance around a circle?
– Circumference: 2πr
• What is the time it takes to complete a cycle
called?
– Period: T
• The formula for the speed an object revolves
or rotates around a circular path is:
2r
s
T
• Ex: A horse on a merry-go-round takes 14.5
seconds to revolve around a ride with a radius
of 3.50 m. How fast is the horse going?
Speed is constant, what about
velocity?
• Velocity is not constant
– Due to a change in the direction that it is pointing
– Velocity is always tangent to the circular path
• The change in the velocity is the acceleration
• The change in the direction is the acceleration
v1
v1
v2
v2
∆v/t = a
• Acceleration points towards the center
• This is called Centripetal Acceleration
– Centripetal means “center seeking”
• What direction is the force pointing then?
Centripetal Force
• A center seeking force that causes objects to
move in a circular motion.
• Points along the radius towards the center of the circular
path.
• What factors could effect the amount of net
force necessary to keep that UCM?
UCM lab
• Determine the mathematical relationship
between _______________________ and the
________________________.
• Determine the mathematical relationship
between the net force required to keep the
object in motion and the speed at which it
travels around the circular path.
Results?
• How is the net force related to the speed for
objects in UCM?
• What would happen to the net force of we
kept the speed constant but doubled the
radius?
• What would happen to the net force if we
kept the speed and radius the same but
doubled the mass?