HELP A rigid rod of mass M and length L is rotating about a fixed point ( ) with
ID: 2103003 • Letter: H
Question
HELP
A rigid rod of mass M and length L is rotating about a fixed point ( ) with angular speed omega0. A force equal to the weight of the rod is applied 1/3 of the way along the rod from the fixed point, opposing its rotation. The force is always perpendicular to the rod as it rotates. No gravity or other forces are acting. Find an expression for the angular acceleration of the rod. Suppose the initial angular speed is 30 rev/sec (clockwise) and the angular acceleration is 15 rad/sec2. How many revolutions does the rod turn through before it starts turn the other way? A uniform rigid rod of length 2b and mass M lies flat and at rest on a frictionless surface. A hockey puck of mass m moving with speed vo collides with it at it end. The collision is elastic. In the special case where the puck is at rest after the collision, find expressions for the center of mass speed of the rod and its angular speed after the collision. Answer in terms of m, M, V0, and/or b. *VCM = *omega = Show that for the puck to be at rest after the collision, the rod must have mass M = 4m.Explanation / Answer
a)
alpha = torque/inertia = (M g (1/3 L))/(1/12 M L^2) = (g (1/3))/(1/12L) = 4 g/L
b)
Theta = w^2/2a = (30*2*3.1416)y2/2/15 = 1184
1184/2/3.1416 = 188 revolutions
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.