Hooke's law and the Young modulus
Watch the whole lecture free
Make a free account to watch every lecture to the end: 1 worked example, 3 practice questions, 4 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.
That was the teaching part. The rest of this lecture is free with an account: 1 worked example, 3 practice questions, 4 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.
No password needed now: we email you a link to set one. Already have an account? Sign in, then come back to this page.
The teaching part (1 min) is free to watch. A free account opens the whole lecture: 1 worked example, 3 practice questions, 4 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
- Why bungee ropes are safe
- Hooke's law
Read the transcript of the teaching part
Last time
Before we start: last time, in Work, power and efficiency, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Why bungee ropes are safe
A bungee jumper falls, the rope stretches, and then pulls her back up. For that, the rope must stretch smoothly and spring back. Whether a material does that depends on a law about force and extension, and on a property of the material itself.
Hooke's law
Hooke's law: the extension of a spring or wire is proportional to the force applied, provided the limit of proportionality is not exceeded. As an equation, F equals k x. The spring constant k is the force per unit extension. A stiff spring has a large k. The graph of force against extension is a straight line through the origin, with gradient k. The extension x is the new length minus the original length, not the length itself.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Hooke's law · Young modulus · Young modulus.
The whole chapter: Deformation of Solids, Deformation of Solids.
Chapter 6.1: Deformation of solids
- Hooke's law and the Young modulus 5 min
Also for A Level Physics 9702
Which topics come up most in A Level Physics 9702 past papers, counted from every paper since 2004: Paper 1 topic frequency, Paper 2 topic frequency.