Homework
Make sure that you have completed:
- Ex 1, p.25-28, Translational Motion
- Q2, Handout, Lab Exercise
Rotational Motion:
- Q1, p.31 Rotational Kinematics
Rotational Kinematics
Radian Measure
Radian Measure is used so that we can easily calculate an arc length, d (m), given an angle, š (Rad) and the radius, r (m).
d = rš
This in turn allows us to relate velocity, v (ms-1) to angular velocity ⍵ (rads-1), in the same way.v = r⍵,
also ⍵ = 2š f
This also allows us to relate acceleration, a (ms-2), to angular acceleration, Ī± (rads-2), in the same way.a = rĪ±
The rotational kinematics work just like the translational kinematic equations when there is a constant acceleration.
- ⍵f = ⍵i + Ī±t ⇔ vf = vi + at
- ⍵f2 = ⍵i2 + 2Ī±š ⇔ vf2 = vi2 + 2ad
- š = ⍵it + ½Ī±t2 ⇔ d = vit + ½a2
- š = ½(⍵i + ⍵f)t ⇔ d = ½(vi + vf)t
Rotational Inertia
Torque
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