Chapter 9253Q9.22No—an external force of gravity acts on the moon. Yes, because its speed is constant.Q9.23The impulse given to the egg is the same regardless of how it stops. If you increase the impact timeby dropping the egg onto foam, you will decrease the impact force.Q9.24Yes. A boomerang, a kitchen stool.Q9.25The center of mass of the balls is in free fall, moving up and then down with the acceleration due togravity, during the 40% of the time when the juggler’s hands are empty. During the 60% of the timewhen the juggler is engaged in catching and tossing, the center of mass must accelerate up with asomewhat smaller average acceleration. The center of mass moves around in a little circle, makingthree revolutions for every one revolution that one ball makes. Letting Trepresent the time for onecycle and Fgthe weight of one ball, we have FTFTJg0603.=and FF=5. The average force exertedby the juggler is five times the weight of one ball.
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