Module 3.4 - Materials Flashcards
How does energy transfer when stretching a spring then releasing?
- As you stretch, the pulling force transfer energy to the ELASTIC store
- When you release, the energy transfers from the elastic to the KINETIC.
Define deformation
The change in shape/size of an object (stretching/squashing/thrusting)
What is elastic deformation?
When a material RETURNS to its original length when a load is removed
What is plastic deformation?
When a material DOES NOT return to its original length when a load is removed - permanent
Describe extension
> Caused by TENSILE forces
Equal and opposite tension forces when stretching
Causes INCREASE in length
POSITIVE extension
Describe compression
> Caused by COMPRESSIVE forces
Equal and opposite but facing EACH OTHER
Causes DECREASE in length
NEGATIVE extension
What happens if a object obeys Hooke’s law?
Its extension will be DIRECTLY PROPORTIONAL to the force applied to deform it, up to its elastic limit
What is Hooke’s law in equation form?
F = kx
F - N
k - N/m
x - m
What does the distance the spring moves whilst stretching equal?
The extension of the spring
How do you found the work done of a spring (energy stored) on a F-x graph?
The area UNDER the graph
How do you work out the Elastic potential energy, E of a material if it obeys Hooke’s law?
E = 1/2Fx = 1/2kx^2
E - J
k - N/m
x - m
F - N
Which - spring, rubber band, plastic strip - has elastic deformation?
Spring and rubber band
Which - spring, rubber band, plastic strip - obey’s Hooke’s law
Spring
For which - spring, rubber band, plastic strip - does all its energy come back out when unloaded?
Spring
Which - spring, rubber band, plastic strip - has plastic deformation?
Plastic strip