1. Two hoops, starting from rest, roll down identical inclinedplanes. The work d
ID: 1725958 • Letter: 1
Question
1. Two hoops, starting from rest, roll down identical inclinedplanes. The work done by nonconservative forces, such as airresistance, is zero (W_nc = 0 J). Both have the same mass M, butone hoop has twice the radius as the other. The moment of inertiafor each hoops is I = Mr^2, where r is its radius. Which, ifeither, has the greater total kinetic energy (translational plusrotational) at the bottom of the incline?A. The smaller hoop
B. Both have the same total kinetic energy
C. The larger hoop
2. An ice skater isspinning on frictionless ice with her arms extended outward. Shethen pulls her arms in towards her body, reducing her moment ofinertia. Her angular momentum is conserved, so as she reduces hermoment of inertia, her angular velocity increases and she spinsfaster. Compared to her initial rotational kinetic energy, herfinal rotational kinetic energy is ...
A. Smaller because her moment of inertia is smaller
B. Larger because her angular speed is larger
C. The same
2. An ice skater isspinning on frictionless ice with her arms extended outward. Shethen pulls her arms in towards her body, reducing her moment ofinertia. Her angular momentum is conserved, so as she reduces hermoment of inertia, her angular velocity increases and she spinsfaster. Compared to her initial rotational kinetic energy, herfinal rotational kinetic energy is ...
A. Smaller because her moment of inertia is smaller
B. Larger because her angular speed is larger
C. The same
Explanation / Answer
2. An ice skater isspinning on frictionless ice with her arms extended outward. Shethen pulls her arms in towards her body, reducing her moment ofinertia. Her angular momentum is conserved, so as she reduces hermoment of inertia, her angular velocity increases and she spinsfaster. Compared to her initial rotational kinetic energy, herfinal rotational kinetic energy is ...
option C is correct.
A. Smaller because her moment of inertia is smaller
B. Larger because her angular speed is larger
C. The same
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