Gravitational potential and kinetic energy
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 3 worked examples, 7 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Two stores you use all the time
- Gravitational potential energy
- The equation, three forms
Read the transcript of the teaching part
Last time
Before we start: last time, in Energy stores, work, potential and kinetic energy, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Two stores you use all the time
A diver stands on a ten metre board. While she stands high up, she has a store of energy because of her height. As she falls, that energy becomes the energy of her movement. Two stores, two equations, and you need both.
Gravitational potential energy
Gravitational potential energy is the energy an object stores because of its height in a gravitational field. It depends on three things: the mass, the gravitational field strength, and the height. The change in gravitational potential energy equals mass times g times the change in height. The unit is the joule. Near the Earth's surface, g is ten newtons per kilogram.
The equation, three forms
The change in potential energy is mass times g times the height change. For the mass, divide by g times the height. For the height, divide by mass times g. Write the one you need, then substitute.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Kinetic and gravitational potential energy · Gravitational potential energy · Kinetic energy.
The whole chapter: Energy, Work and Power, Energy, Work and Power.
Chapter 1.7: Energy, work and power
- Energy stores, conservation and work done 5 min
- Gravitational potential and kinetic energy 6 min
- Power and efficiency 6 min
- Energy resources 7 min
Also for O Level Physics 5054
Which topics come up most in O Level Physics 5054 past papers, counted from every paper since 2004.