Rolling – It’s More Complicated than
You Thought!
Draw the Path of the ✕ on Your Paper
for at Least 2 Revolutions
The Red LED traces the path of the ✕. The
Orange LED traces the path of the center.
Make any Necessary Correction to
Your Drawing
A wheel rolls by you at constant velocity.
Which part of the wheel is moving the fastest?
A. the bottom
B. the center
C. the top
D. the point out in front
E. all points move with the same speed
Which part of the wheel is moving the slowest?
A. the bottom
B. the center
C. the top
D. the point out in front
E. all points move with the same speed
A Rolling Wheel is the Synthesis of a
Rotating Wheel and a Translating Wheel
+
V=0
Rotatin
g
Wheel
=
V
Translating
Wheel
V
Rolling
Wheel
Long Exposure Photograph of Rolling
Bike Wheel. Fastest Spokes are Blurred
A Flashing LED is Attached to a Hollow
Cylinder and Rolled Down a Ramp
The Fastest Point on a Rolling
Object is at the Top
The Slowest Point on a Rolling
Object is at the Bottom
The Fastest Point on a Rolling
Object is at the Top
The Slowest Point on a Rolling
Object is at the Bottom
The Point on a Rolling Object in
Contact with the Ground has a
Velocity of Zero!
How fast is the bottom of a tank
tread moving?
When a car is travelling at 65 mph, which part
of the wheel is going that fast too?
A. the bottom
B. the center
C. the top
D. the point out in front
E. all points move with the same speed
There are 2 ways of visualizing a rolling
object, rotation and translation combined
and pure rotation.
Rotation and
translation analyzes
rolling into 2 separate
motions:
Pure rotation
synthesizes these
motions into 1
motion, an object
trying to rotate about
its contact point:
+
What is the rotational inertia of a
hollow sphere rotating about a
point on its surface if I about its
center is: I  2 mr2
CM
2 2
A : I  mr
3
 3 2
B : I  mr
2
2 
C : I  mr
3
4 2
D : I  mr
3
5 2
E : I  mr
3
Show that the acceleration of a hollow
sphere on a ramp is equal to: 3 gsin(  )
5

Show that the acceleration of a hollow
cylinder on a ramp is equal to: 1 gsin(  )
2

A solid cylinder is released from rest from
height h and rolls down a ramp without
slipping, then rolls up a frictionless ramp. Its
final height is on the frictionless ramp is
A. equal to its initial height
B. less than its initial height
C. greater than its initial height
D. zero