Ever wondered why a spring bounces back or why a...
Physics546 views·Updated May 28, 2026·4 pagesUnderstanding Forces and Elasticity in Physics
Zofia@zofia_577
1 / 4
1
of 4
Forces and Elasticity Basics
You can't just use one force to change an object's shape - you need at least two forces working together. Think about bending a ruler: one hand pushes down whilst the other holds it steady.
Deformation simply means changing an object's shape or size by applying forces. This happens in two main ways: elastic deformation (like stretching a rubber band that snaps back) and inelastic deformation .
When objects get longer under force, that's called extension. When they get shorter or squashed, that's compression. Hooke's Law gives us a neat formula to work with springs: Force = Spring Constant × Extension.
Quick Tip: Remember F = k × e - Force equals spring constant times extension!
2
of 4
Hooke's Law in Action
Let's see Hooke's Law working with a real example. If you apply 3 N of force to a spring and it stretches by 0.15 m, you can find the spring constant by rearranging the formula.
Spring Constant = Force ÷ Extension = 3 ÷ 0.15 = 20 N/m. This tells you how stiff the spring is - the higher the number, the stiffer it gets.
But here's the catch: Hooke's Law only works up to the limit of proportionality. Beyond this point, doubling the force won't double the extension anymore. The spring starts behaving differently and might not return to its original shape.
Remember: A stiffer spring has a higher spring constant and needs more force to stretch the same distance!
3
of 4
Elastic Potential Energy
When you stretch a spring, you're actually storing energy in it - this is called elastic potential energy. It's like loading a catapult; the energy gets released when the spring returns to its normal length.
The formula is: Elastic Potential Energy = 0.5 × Spring Constant × (Extension)². Notice that extension is squared - this means small changes in stretching create big changes in stored energy.
Here's a worked example: A spring with a 3 N/m spring constant stretched by 50 cm (0.5 m). The stored energy = 0.5 × 3 × (0.5)² = 0.5 × 3 × 0.25 = 0.375 J.
Top Tip: Always convert centimetres to metres before calculating - it's a common exam mistake to forget this step!
4
of 4
Understanding the Energy Calculation
The previous calculation shows why the squared term matters so much. When the extension was 0.5 m, squaring it gave us 0.25 m². This dramatically affects the final energy value.
Elastic potential energy is measured in joules (J), just like other forms of energy. As long as you don't stretch beyond the limit of proportionality, all the work you put in gets stored as potential energy.
This stored energy explains why springs are so useful - from car suspension to trampolines, they absorb energy and release it back efficiently.
Key Point: The energy stored increases rapidly as you stretch further - double the extension means four times the energy!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar content
Most popular content in Physics
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user
Physics546 views·Updated May 28, 2026·4 pagesUnderstanding Forces and Elasticity in Physics
Zofia@zofia_577
Ever wondered why a spring bounces back or why a rubber band snaps into place? Forces and elasticity explain how objects change shape when pushed, pulled, or squashed - and whether they return to normal afterwards.
1
of 4
Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Forces and Elasticity Basics
You can't just use one force to change an object's shape - you need at least two forces working together. Think about bending a ruler: one hand pushes down whilst the other holds it steady.
Deformation simply means changing an object's shape or size by applying forces. This happens in two main ways: elastic deformation (like stretching a rubber band that snaps back) and inelastic deformation .
When objects get longer under force, that's called extension. When they get shorter or squashed, that's compression. Hooke's Law gives us a neat formula to work with springs: Force = Spring Constant × Extension.
Quick Tip: Remember F = k × e - Force equals spring constant times extension!
2
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Hooke's Law in Action
Let's see Hooke's Law working with a real example. If you apply 3 N of force to a spring and it stretches by 0.15 m, you can find the spring constant by rearranging the formula.
Spring Constant = Force ÷ Extension = 3 ÷ 0.15 = 20 N/m. This tells you how stiff the spring is - the higher the number, the stiffer it gets.
But here's the catch: Hooke's Law only works up to the limit of proportionality. Beyond this point, doubling the force won't double the extension anymore. The spring starts behaving differently and might not return to its original shape.
Remember: A stiffer spring has a higher spring constant and needs more force to stretch the same distance!
3
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Elastic Potential Energy
When you stretch a spring, you're actually storing energy in it - this is called elastic potential energy. It's like loading a catapult; the energy gets released when the spring returns to its normal length.
The formula is: Elastic Potential Energy = 0.5 × Spring Constant × (Extension)². Notice that extension is squared - this means small changes in stretching create big changes in stored energy.
Here's a worked example: A spring with a 3 N/m spring constant stretched by 50 cm (0.5 m). The stored energy = 0.5 × 3 × (0.5)² = 0.5 × 3 × 0.25 = 0.375 J.
Top Tip: Always convert centimetres to metres before calculating - it's a common exam mistake to forget this step!
4
of 4Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Understanding the Energy Calculation
The previous calculation shows why the squared term matters so much. When the extension was 0.5 m, squaring it gave us 0.25 m². This dramatically affects the final energy value.
Elastic potential energy is measured in joules (J), just like other forms of energy. As long as you don't stretch beyond the limit of proportionality, all the work you put in gets stored as potential energy.
This stored energy explains why springs are so useful - from car suspension to trampolines, they absorb energy and release it back efficiently.
Key Point: The energy stored increases rapidly as you stretch further - double the extension means four times the energy!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
Where can I download the Knowunity app?
You can download the app from Google Play Store and Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar content
Most popular content in Physics
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user