For an extended object, such as a baseball bat, the trajectory of any given point on the object may be quite complicated. However, the trajectory of one point, the center of mass, is just the same parabolic trajectory that a ball would follow.

The center of gravity is a term that refers to the average force of gravity on an extended object. Except for very large objects, such as the moon, the center of gravity and the center of mass are the same point. An object (such as a building) will be in stable equilibrium if a line dropped from the center of mass falls within the base of support as shown below.

If you complete all of the practice quizzes during the semester, you may replace your lowest two in-class quizzes with the highest average of all your on-line quizzes. Since you may take the practice quizzes as often as you like, your highest average should be pretty good. However, in order to keep track, you must fill out the student name and id# part of the form.

For this quiz, just click on the part(s) of the figure to correctly answer the problem.

Question 1. Locate the center of mass for each of the two uniform objects in the figure below.

 

 

 

Question 2.In the figure below, "x" marks the location of the center of gravity for each truck parked on the hill. Select the truck(s) which are unstable and will tip over.