Home · A-Level 9702 · Work, energy and power · Kinetic and potential energy · Practice
AS · Practice questions · Kinetic and potential energy

Swap height for speed.

Six original Cambridge-style questions on GPE and KE changes, finding speed from a drop, and energy conservation.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Two stores, one total.

01
Analysis
[2 marks]

Define kinetic energy and state the formula used to calculate it.

  • Kinetic energy is the energy a body has because of its motion ✓
  • Eₖ = ½mv² ✓
02
Analysis
[2 marks]

Find the gravitational potential energy gained when a 5.0 kg mass is lifted through 2.0 m (g = 9.8 m s⁻²).

  • ΔEₚ = mgΔh = 5.0 × 9.8 × 2.0 ✓
  • ΔEₚ = 98 J ✓
03
Analysis
[3 marks]

A 0.20 kg ball is dropped from rest from a height of 5.0 m. Using energy conservation (g = 9.8 m s⁻²), find its speed on landing.

  • mgΔh = ½mv², and the mass cancels ✓
  • v = √(2gΔh) = √(2 × 9.8 × 5.0) ✓
  • v = 9.9 m s⁻¹ ✓
04
Analysis
[3 marks]

A 1200 kg car speeds up from 10 m s⁻¹ to 20 m s⁻¹. Find the increase in its kinetic energy.

  • KE at 20 = ½ × 1200 × 20² = 240 000 J ✓
  • KE at 10 = ½ × 1200 × 10² = 60 000 J ✓
  • Increase = 240 000 − 60 000 = 180 000 J = 180 kJ ✓
05
Analysis
[3 marks]

A pendulum bob is pulled aside until it is 0.45 m above its lowest point, then released. Find its speed at the lowest point (g = 9.8 m s⁻²).

  • GPE lost becomes KE: mgΔh = ½mv² ✓
  • v = √(2gΔh) = √(2 × 9.8 × 0.45) ✓
  • v = 3.0 m s⁻¹ ✓
06
Analysis
[2 marks]

Explain why, for a constant braking force, doubling a car's speed roughly quadruples its braking distance.

  • Kinetic energy Eₖ = ½mv² is proportional to v², so doubling v gives four times the KE ✓
  • The braking force does work Fd to remove this KE, so d ∝ KE ∝ v², and the distance quadruples ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.