Materials Flashcards
What is the formula for the volume of a sphere?
(4/3) * pi * r^3
What is the formula for the volume of a cylinder
pi * r^2 * h
Volume of a regular prism
cross section area * h
What is the SI unit for length?
metres (m)
What is the definition of density
The mass per unit volume
Which factors must be kept constant for the density to remain constant
the material, the temperature, the pressure
What is the definition of weight
The force on an object due to gravity
What is the definition of mass
the amount of substance in kg
What is Hooke’s Law
Force is proportional to extension, provided the limit of proportionality has not been reached
What is the definition of elastic limit
The point before which a spring will return to its original length when the load is removed. After this point, plastic (permanent) deformation will occur
Explain the differences in tension (T), extension(ΔL), and spring stiffness constant (k) for identical springs in series and parallel.
Series:
- T: weight
- total ΔL: 2 * ΔL
- k for combination: 1/2 * k
Parallel:
- T: 1/2 * weight
- total ΔL: 1/2 * ΔL
- k for combination: 2 * k
In a graph of force vs extension, what value can be found by working out the area under the graph
the work done in stretching the spring
What is the formula for elastic potential energy
E = 1/2 * F * ΔL
or
E = 1/2 * k * (ΔL)^2
What does the area under the loading line on a force extension graph represent
the energy converted to elastic potential, or work done.
What does the area under the unloading line on a force extension graph represent
The energy returned from elastic potential to kinetic energy and gravitational potential energy.
