http://www.ck12.org Chapter 9. Rotational Motion
b. What is the magnitude (value) of this force, in Newtons?
c. What is the moment arm of the torque produced by weightA?
d. What is the magnitude of this torque, inN·m?
e. Repeat parts (a – d) for weightsBandC.
f. Calculate the net torque. Is the plank balanced? Explain.- There is a uniform rod of mass 2.0 kg of length 2.0 m. It has a mass of 2.6 kg at one end. It is attached to the
ceiling.40 m from the end with the mass. The string comes in at a 53degree angle to the rod.
a. Calculate the total torque on the rod.
b. Determine its direction of rotation.
c. Explain, but don’t calculate, what happens to the angular acceleration as it rotates toward a vertical
position.
Answers- At End. Discuss in class. Moment of inertia at the end 1/3 ML^2 at the center 1/12 ML^2 and torque,τ=Iα
change the in the same way - a. weight b. 19.6 N c. plank’s length( 0 .8m)left of the pivot d. 15.7 N m, e. Ba. weight, Bb. 14.7 N, Bc.
plank’s length( 0 .3m)left of the pivot, Bd. 4.4 N m, Ca. weight, Cb. 13.6 N, Cc. plank’s length( 1 .00 m)
right of the pivot, Cd. 13.6 N m, f) 6.5 N m CC, g) no, net torque doesn’t equal zero - CCW