Hooke’s Law Flashcards
What can forces cause?
- change in speed (acceleration/deceleration)
- change in shape
- change in direction
Compression
Forces that cause squashing
- decrease in length
Tension
Forces that cause stretching
- increase in length, or extension
Hooke’s Law
The extension of a spring is proportional to the amount of force applied to it.
Formula for Hooke’s Law
F = kΔx
F = applied force (in Newtons, N)
Δx = the extension (in metres, m)
k = spring constant (in N/m)
Δx = stretched length - original length
What is elastic behaviour?
Elastic behaviour is the ability of a material to recover its original shape after the forces causing deformarion have been removed.
What is plastic behaviour?
Plastic (or inelastic) behaviour is the behaviour of a material that stays deformed after you have taken the force away - it is a sign of plasic behaviour.
Limit of proportionality
Elastic material will behave elastically up to a certain limit. This is known as the limit of proportionality.
If too much force is applied, they will deform permanently and no longer obey Hooke’s Law.
When the force is removed, they will not return to their original length.
Draw a force-extension graph labelling the limit of proportionality
N/a
Spring constant
The spring constant measures how stiff the spring is
Draw a force-extension graph of a stiff spring
N/a
Draw a force-extension graph of a softer spring
N/a
Draw a force-extension graph of an even softer spring
N/a
Do metal wires obey Hooke’s Law?
Yes
Do rubber bands obey Hooke’s Law?
No
