If a hollow sphere and a solid sphere of the same mass and radius roll down the

Practice Questions

Q1
If a hollow sphere and a solid sphere of the same mass and radius roll down the same incline, which one reaches the bottom first?
  1. Hollow sphere
  2. Solid sphere
  3. Both reach at the same time
  4. Depends on the angle of incline

Questions & Step-by-Step Solutions

If a hollow sphere and a solid sphere of the same mass and radius roll down the same incline, which one reaches the bottom first?
Correct Answer: Solid sphere
  • Step 1: Understand that both spheres have the same mass and radius.
  • Step 2: Know that when objects roll down an incline, they have both translational (moving forward) and rotational (spinning) motion.
  • Step 3: Learn about moment of inertia, which is a measure of how difficult it is to change an object's rotation. A solid sphere has a smaller moment of inertia than a hollow sphere.
  • Step 4: Realize that a smaller moment of inertia means the solid sphere can convert more of its potential energy into translational kinetic energy (forward motion) rather than rotational kinetic energy (spinning).
  • Step 5: Conclude that since the solid sphere accelerates faster due to its smaller moment of inertia, it will reach the bottom of the incline first.
  • Moment of Inertia – The distribution of mass in an object affects its rotational motion; a lower moment of inertia allows for faster acceleration when rolling.
  • Rolling Motion – Understanding the difference between translational and rotational motion is crucial for analyzing objects that roll down an incline.
  • Energy Conservation – The conversion of potential energy to kinetic energy (both translational and rotational) plays a key role in determining which object reaches the bottom first.
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