(b) (c) 9.62. Set Up: The outer radius is The angular speed is greatest when r is smallest. Solve: (a) when so (b) Find r when The diameter is 4.84 cm. (c) gives is negative since the rotation rate slows as the tracking spirals outward. 9.63. Set Up: For alignment, the earth must move through 45° more than Mars, in the same time t . Solve: 9.64. Set Up: When it rolls without slipping, When there is no friction the angular speed of rotation is constant. Take upward and let in the valley. Solve: (a) Find the speed in the level valley: Therefore, so and Find the height H it goes up the other side. Its rotational kinetic energy stays constant as it rolls on the frictionless surface. (b) Some of the initial potential energy has been converted into rotational kinetic energy so there is less potential energy at the second height H than at the first height 9.65. Set Up: My total mass is I model my head as a uniform sphere of radius 8 cm. I model my trunk and legs as a uniform solid cylinder of radius 12 cm. I model my arms as slender rods of length 60 cm.
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