Concepts Of Physics MCQ Edition [Volume 1]
- Exam
- Concepts Of Physics MCQ Edition [Volume 1]
- Subject
- Physics
- Chapter
- Rotational Mechanics
Concepts Of Physics MCQ Edition [Volume 1] · Physics · Rotational Mechanics
A solid sphere and a hollow sphere, both possessing the same mass...
A solid sphere and a hollow sphere, both possessing the same mass and identical radii, are rolled down a rough inclined plane.
Options
- AThe solid sphere arrives at the bottom with a greater speed.
- BBoth spheres will arrive at the bottom with the same linear momentum.
- CThe hollow sphere arrives at the bottom first.
- DThe solid sphere arrives at the bottom with a greater kinetic energy.
Correct answer
A. The solid sphere arrives at the bottom with a greater speed.
Step-by-step solution
Let be the mass and be the radius of both spheres.
The moment of inertia of the solid sphere is I_H = \dfrac{2}{3}MR^2h
Since for pure rolling:
Mgh = \dfrac{1}{2}Mv^2 \left(1 +\dfrac{I}{MR^2}\right)
\sqrt{\dfrac{2gh}{1 + \dfrac{I}{MR^2}}}
Since , the denominator is smaller for the solid sphere, giving . Thus, the solid sphere arrives at the bottom with a greater speed.
The acceleration of a rolling body is \dfrac{g \sin \theta}{1 + \dfrac{I}{MR^2}}. Since , , meaning the solid sphere reaches the bottom first.
Linear momentum is . Since , .
Total kinetic energy at the bottom is equal to the initial potential energy , which is the same for both spheres.
The moment of inertia of the solid sphere is I_H = \dfrac{2}{3}MR^2h
Since for pure rolling:
Mgh = \dfrac{1}{2}Mv^2 \left(1 +\dfrac{I}{MR^2}\right)
\sqrt{\dfrac{2gh}{1 + \dfrac{I}{MR^2}}}
Since , the denominator is smaller for the solid sphere, giving . Thus, the solid sphere arrives at the bottom with a greater speed.
The acceleration of a rolling body is \dfrac{g \sin \theta}{1 + \dfrac{I}{MR^2}}. Since , , meaning the solid sphere reaches the bottom first.
Linear momentum is . Since , .
Total kinetic energy at the bottom is equal to the initial potential energy , which is the same for both spheres.