Conservation of Energy with Rotation Video Lessons

Concept

# Problem: An Unfair Race This applet shows the results of releasing a frictionless block and a rolling disk with equal masses from the top of identical inclined planes. Part A Which of the following is the best explanation of the results shown in the applet? Which of the following is the best explanation of the results shown in the applet? a) The disk loses energy to friction as it rolls, but the box is frictionless and so it speeds up more quickly and gets to the bottom first. b) The potential energy of the disk is converted into translational and rotational kinetic energy, so the translational speed grows more slowly than that of the box, which has no rotational energy. c) The net forces on the two objects are equal, but the force on the disk gets partially used up in creating the torque necessary to make it roll. d) The net forces on the two objects are equal, but the force on the disk is not directed parallel to the ramp, and so does not create as great an acceleration down the ramp.

###### FREE Expert Solution

The rolling disk has both translational kinetic energy and rotational kinetic energy. The translational kinetic energy will grow more slowly compared the box that converts potential energy to translational kinetic energy only.

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###### Problem Details

An Unfair Race This applet shows the results of releasing a frictionless block and a rolling disk with equal masses from the top of identical inclined planes.

Part A

Which of the following is the best explanation of the results shown in the applet? Which of the following is the best explanation of the results shown in the applet?

a) The disk loses energy to friction as it rolls, but the box is frictionless and so it speeds up more quickly and gets to the bottom first.

b) The potential energy of the disk is converted into translational and rotational kinetic energy, so the translational speed grows more slowly than that of the box, which has no rotational energy.

c) The net forces on the two objects are equal, but the force on the disk gets partially used up in creating the torque necessary to make it roll.

d) The net forces on the two objects are equal, but the force on the disk is not directed parallel to the ramp, and so does not create as great an acceleration down the ramp.