Hey guys, i dont know why its always two or three problems on my homework that always stump me. Any help and tips are appreciated(adsbygoogle = window.adsbygoogle || []).push({});

1) A wheel with a weight of 393N comes off a moving truck and rolls without slipping along a highway. At the bottom of a hill it is rotating at an angular velocity of 27.6 rad/s. The radius of the wheel is 0.645m and its moment of inertia about its rotation axis is 0.800MR^2 . Friction does work on the wheel as it rolls up the hill to a stop, at a height of above the bottom of the hill; this work has a magnitude of 3536J.

Part A) Calculate h. Use 9.81m/s^2 for the acceleration due to gravity.

I tried an energy approach and got an expression for h as follows:

h=(2*3536)/(I*omega^2) where I was moment of inertia....i think i messed up in the friction part though. Any advice?

2) A large turntable rotates about a fixed vertical axis, making one revolution in a time of 5.90s. The moment of inertia of the turntable about this axis is 1250kg*m^2 . A child with a mass of 45.0kg, initially standing at the center of the turntable, runs out along a radius.

Part A) What is the angular speed of the turntable when the child is a distance of 2.40m from the center? (Assume that you can treat the child as a particle.)

No idea where to even being on this one.

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# Homework Help: Rotational Dynamics and Equillibrium HELP

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