A ball rolls down a ramp of height h. If it starts from rest, what is its final

Practice Questions

Q1
A ball rolls down a ramp of height h. If it starts from rest, what is its final speed at the bottom?
  1. √(gh)
  2. √(2gh)
  3. √(3gh)
  4. √(4gh)

Questions & Step-by-Step Solutions

A ball rolls down a ramp of height h. If it starts from rest, what is its final speed at the bottom?
Correct Answer: √(2gh)
  • Step 1: Understand that the ball starts at a height 'h' and has potential energy due to its height.
  • Step 2: Remember the formula for potential energy (PE) which is PE = mgh, where 'm' is mass, 'g' is acceleration due to gravity, and 'h' is height.
  • Step 3: When the ball rolls down, this potential energy converts into kinetic energy (KE).
  • Step 4: The formula for kinetic energy is KE = (1/2)mv^2, where 'v' is the final speed of the ball.
  • Step 5: Set the potential energy equal to the kinetic energy: mgh = (1/2)mv^2.
  • Step 6: Notice that 'm' (mass of the ball) can be canceled from both sides of the equation since it is present in both terms.
  • Step 7: You are left with the equation: gh = (1/2)v^2.
  • Step 8: To solve for 'v', multiply both sides by 2: 2gh = v^2.
  • Step 9: Take the square root of both sides to find 'v': v = √(2gh).
  • Conservation of Energy – The principle that energy cannot be created or destroyed, only transformed from one form to another.
  • Potential Energy – The energy stored in an object due to its height above the ground, calculated as mgh.
  • Kinetic Energy – The energy of an object in motion, calculated as (1/2)mv^2.
  • Kinematics – The study of motion, which in this case relates to the final speed of the ball.
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