Ch. 12 – Rotational Motion. I. Torque:. Measurement of a force perpendicular to a lever arm. A. T = F perp d (SI Units = Nm). B. Balanced Teeter-Totters:. To balance, torques must be equal!. 1. F perp d = F perp d. 2. If one side has a larger Force (weight) than the other,.
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Measurement of a force perpendicular to a lever arm
A. T = Fperpd (SI Units = Nm)
B. Balanced Teeter-Totters:
To balance, torques must be equal!
1. Fperpd = Fperpd
2. If one side has a larger Force (weight) than the other,
the distance (length of lever) must change inversely
C. Unbalanced Teeter-Totters:
The CG is always on the side with the most torque
in their rotational motion.
II. Rotational Inertia (I):
A. Equation: I = mr2
1. SI units = kgm2
2. The greater the distance the mass is from the CG,
the greater the rotational inertia (balancing a broom)
Involves linear motion and rotational motion
*** a barrel of water vs. a barrel of ice ***
C. Angular Momentum:
Like regular momentum, but is the product
of rotational inertia and rotational velocity
*** Angular momentum = I W ***
D. Conservation of Angular Momentum:
Decreasing inertia of a
system increases the
velocity, and vice versa
(ice skaters, etc.)
*** IWbefore = IWafter ***