A roller coaster starts from rest at a height of 50 m. What is its speed at the

Practice Questions

Q1
A roller coaster starts from rest at a height of 50 m. What is its speed at the lowest point? (g = 9.8 m/s²)
  1. 10 m/s
  2. 20 m/s
  3. 30 m/s
  4. 40 m/s

Questions & Step-by-Step Solutions

A roller coaster starts from rest at a height of 50 m. What is its speed at the lowest point? (g = 9.8 m/s²)
  • Step 1: Understand that the roller coaster starts from a height of 50 meters and is initially at rest, meaning its initial speed is 0 m/s.
  • Step 2: Recognize that as the roller coaster descends, potential energy (due to its height) is converted into kinetic energy (due to its speed).
  • Step 3: Use the formula for potential energy: PE = mgh, where m is mass, g is the acceleration due to gravity (9.8 m/s²), and h is height (50 m).
  • Step 4: Use the formula for kinetic energy: KE = 0.5mv², where v is the speed we want to find.
  • Step 5: Set the potential energy equal to the kinetic energy at the lowest point: mgh = 0.5mv².
  • Step 6: Notice that mass (m) cancels out from both sides of the equation, simplifying it to gh = 0.5v².
  • Step 7: Rearrange the equation to solve for v: v² = 2gh.
  • Step 8: Substitute the values for g (9.8 m/s²) and h (50 m) into the equation: v² = 2 * 9.8 * 50.
  • Step 9: Calculate the right side: v² = 980.
  • Step 10: Take the square root of both sides to find v: v = sqrt(980).
  • Step 11: Calculate the square root: v ≈ 31.3 m/s.
  • Conservation of Energy – The principle that energy cannot be created or destroyed, only transformed from one form to another, in this case from potential energy to kinetic energy.
  • Kinetic and Potential Energy – Understanding the relationship between potential energy (mgh) at height and kinetic energy (0.5mv²) at the lowest point.
  • Gravitational Acceleration – The constant acceleration due to gravity (g = 9.8 m/s²) that affects the motion of the roller coaster.
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