Rotational Motion

Be sure to type all work, diagrams, explanations, and final answers as it is too difficult to read hand-written work after going through the various systems to get to your instructor. Also, this is good practice as you will have to type the midterm and final exam free response items as well.

1. Sir Isaac Newton twirls his corded headphones horizontally above his head just for fun. The headphones have a mass of15g and are held by its cord which is6.0 cm long.

1. If the force of tension on the cord is0.075N, how long does it take to make one complete revolution? (10 points)

1. If the cord lengthens to8.0cmand Sir Isaac Newton keeps the headphones rotating at the same speed as before, how much tension will there be in the cord? (10 points)

1. Tweedledee and Tweedledum are at the playground enjoying the merry-go-round. Tweedledee is spinning the merry-go-round while Tweedledum (m =60kg) tries desperately to hold on. The merry-go-round has a diameter of3.5 m, and Tweedledum is holding on to the outer handles. Tweedledum can hold on with a maximum force of 600 N before he flies off. If Tweedledee can get the merry-go-round to complete one revolution in3.5s, can Tweedledum hold on? Explain your reasoning. (10 points)

1. Tarzan (m =85kg) tries to cross a river by swinging from a vine. The vine is10.2mlong, and his speed at the bottom of the swing is8.0 m/s. Tarzan does not know that the vine has a breaking strength of1000N. Does he make it safely across the river? Explain your reasoning. (10 points)