Unit 6 Flashcards
What is hooke’s law?
Force needed to stretch spring is directly proportional to extension of spring from its natural length, provided elastic limit has not been reached.
What is the equation for Hooke’s law?
F = Kx
K - Spring constant
What is elastic limit?
When spring is stretched permanently and won’t return to its natural shape (this is called plastic behaviour)
What is elastic strain energy?
When a spring or wire is stretched potential energy is stored.
What are the two equations for energy stored in a spring?
E = 1/2 Fx
E = 1/2 kx^2
What is the equation for tensile stress?
Tensile force/cross-sectional area
or F/A
What is breaking stress?
stress required to cause a material to break
What is the equation for Tensile strain?
Extension / original length
or x/l
What is the unit for tensile stress?
Pa (pascals) or NM-²
What is the area of a circle?
A = πd ²/4
What does the Young Modulus measure?
Stiffness of a material
What are the two equations for the young modulus?
Tensile stress/tensile strain
or E = σ/ε
or E = FL/Ax
What is the unit for Young modulus?
Pa (Pascal)
What is used to measure the diameter of a string/wire etc.?
Micrometer
What is momentum?
Measure of how difficult it is to stop a moving object
What is the equation for momentum?
Momentum = mass x velocity
p = mv
What is the definition of the conservation of momentum?
In a closed system, the total momentum before an event and the total momentum after an event area the same.
What does the area under a force x time graph give?
The change in momentum.
What energy is conserved in an elastic collision?
Kinetic energy
What takes place in an inelastic collision?
Some kinetic energy is transformed into thermal or other forms of energy
