A uniform narrow bar, resting on frictionless ice, is given a transverse horizontal impulse at one end as shown. The center of mass of the bar COM will then:
A) remain at rest
B) move in a circle
C) move in a straight line
D) move in a parabola
E) move along some other curve

Question

A uniform narrow bar, resting on frictionless ice, is given a transverse horizontal impulse at one end as shown. The center of mass of the bar COM will then: 
A) remain at rest 
B) move in a circle 
C) move in a straight line 
D) move in a parabola 
E) move along some other curve

Quizplus · Accepted Answer

Since the bar is resting on frictionless ice, there will be no external forces acting on it after the impulse. Therefore, the center of mass of the bar will continue moving with a constant velocity in the same direction as the impulse, which is a straight line. Option C is the correct answer. The bar will not move in a circle, parabola, or any other curve because there are no external forces to cause it to do so. The bar will also not remain at rest since it was given a horizontal impulse.

A Uniform Narrow Bar, Resting on Frictionless Ice, Is Given