Energy in Materials
Physics: AQA A Level, topic 4.2.3
Energies in Spring Systems
In a simple spring system under a load, the spring oscillates. The total energy of the system remains constant, but the components of this energy (kinetic, gravitational potential and elastic potential) can vary.
Total energy
- A spring system obeys the law of conservation of energy.
- The total energy at all points in an oscillation is the same.
Elastic potential energy
- Elastic potential energy stored in a spring is:
- This is equal to the area under a force-extension graph.
- Using Hooke's law ():
Energy Conservation in Transport Design
Safety features of vehicles rely on specific material properties.
Energy issues
- In an impact (such as a car crash), a great deal of energy can be transferred to the passengers.
- This could cause significant injury. Vehicles are designed to redirect this energy away from passengers.
Crumple zones
- Crumple zones are parts of a vehicle which permanently deform.
- Crumple zones show plastic behaviour.
- The energy of impact is redirected towards plastically deforming the crumple zones. So people are less likely to be injured.
Test yourself on Energy in Materials
Which statements are true about an oscillating spring?
Explain how the energy of a spring varies as it oscillates.
Which statements about crumple zones are true?