A disc, a hoop, and a sphere of the same mass and radius are rolled down from a frictionless, inclined plane. Which has a greater speed on reaching the ground?
Correct answer: C. Sphere
- A. Disc
- B. Loop
- C. Sphere
- D. All have the same speed
Explanation
The sphere has most of its mass near the axis of rotation, so it will have the smallest moment of inertia and will reach the ground first.The disc has its mass uniformly distributed, so will have a greater moment of inertia and will arrive second.The hoop has all its mass concentrated away from the center, so will have the greatest moment of inertia. It will arrive last, but will then travel farther away on the horizontal plane than the other shapes, as it will have stored more of the original potential energy in the form of rotational energy.
Last updated
About Kinetic Energy
Kinetic energy is the energy of motion, given for a nonrelativistic object by K = ½mv², so it depends on mass and the square of speed. Questions connect kinetic energy with work through the work energy theorem, calculate changes in kinetic energy, and distinguish it from momentum and potential energy.
Practise Work and Energy
748 free Work and Energy MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
The kinetic energy of a body is doubled when its
A body of mass 5 kg moves at 4 m s-1. Its kinetic energy is
If the speed of a car is doubled, its kinetic energy becomes
A body of mass 1 kg has kinetic energy 50 J. Its speed is
If the momentum of an object is increased twice, then what will be the kinetic energy?