Elastic Deformation - O Level Physics Cheat Sheet
1. Elastic Deformation
Elastic deformation happens when an object changes shape or size due to a force but returns to its original
form when the force is removed. This only occurs within the elastic region.
2. Force Causes Change in Size/Shape
Forces can:
- Stretch (rubber band)
- Compress (sponge)
- Bend (ruler)
- Twist (towel)
These all count as changes in shape and/or size.
3. Spring Constant & Hooke's Law
Hooke's Law: F = kx
Where:
- F = Force (N)
- k = Spring constant (N/m)
- x = Extension (m)
Spring constant is defined as the force per unit extension: k = F / x
4. Load-Extension Graph
Elastic Deformation - O Level Physics Cheat Sheet
On the graph:
- X-axis = Extension (m)
- Y-axis = Force (N)
- Straight line = Obeys Hooke's Law
- Curved line = No longer proportional
- The red dashed line marks the 'Limit of Proportionality'.
5. Experimental Setup
To plot the graph:
1. Hang spring from clamp
2. Measure its original length
3. Add weights gradually
4. Measure new length and calculate extension
5. Plot Force vs Extension
6. Limit of Proportionality
This is the point beyond which extension is no longer directly proportional to the load.
Elastic Deformation - O Level Physics Cheat Sheet
Hooke's Law is only valid up to this point. It is where the graph stops being straight.
Summary Table
Concept | Description
--------|------------Elastic deformation | Reversible change in shape
Spring constant (k) | Force per unit extension
Hooke's Law | F = kx
Limit of proportionality | Beyond this, F != kx
Load-extension graph | Graph of force vs stretch