Download Angular Momentum - Houghton College

Unit: Rotation
I. Coordinates:  = s/R,  = vt/R,  = at/R
II. Kinematics: same form, new variables
III. Energy:
A.
Moment of Inertia (rotational mass): I = mr2
B.
Rotational Kinetic Energy: K = (1/2)I 2
C. Rolling Bodies: only the type of shape matters
IV. Torque (rotational force):  = rFsin
V. Angular Momentum:
A.
L = rpsin = I
B.
t = L
C.
Conservation
today
A ball rotates around on a string. If the string length were doubled and the velocity
held constant, what would happen to the angular momentum?
A solid disk and a hoop of equal radius both rotate around at the same frequency. If
they weigh the same amount, which has the greater angular momentum?
a) the disk
b) the hoop
c) they have the same angular momentum
A merry-go-round rotates counterclockwise (from above). Which way does the
angular momentum vector point?
A 10kg merry-go-round rotates counterclockwise (from above). A child leans up
against the outside edge (2m from the middle), providing a constant frictional force.
Which direction does the torque vector point?
A 10kg merry-go-round rotates counterclockwise (from above). A child leans up
against the outside edge (2m from the middle), providing a constant frictional force of
30N. At what rate does the angular momentum decrease?
You are riding your bicycle through campus. Which way does the angular momentum
vector of your tires point?
A 5,000kg plane is flying 200m/s at a constant altitude of 8,000m. What is the angular
momentum of the plane about you when you see the plane from the quad at
Houghton College.
The system below is released from rest. What is the direction of the net torque on the
pulley?
20kg
10kg
You are riding your bicycle down Rt. 19. You suddenly jerk your handle bar to the left.
What does this cause the tire to do?