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.
What does the area between the lines on a force extension graph represent
The energy lost as heat
What is the definition of stress
The ratio of force to cross sectional area
What is the definition of strain
the ratio of extension to original length
What is the definition of the Young Modulus
The ratio of tensile stress to tensile strain, it is a constant for a particular material
What is the units for Young’s Modulus, stress, and strain
Young’s Modulus (E): Pa
Stress (σ): Pa
Strain (ε): No units
the Young’s Modulus is a measure of what
The stiffness of a material
The gradient of the straight part of a stress strain graph represents what
The Young’s Modulus
What does the area under a stress strain graph represent
the work done per unit volume
What is the ultimate tensile stress of a material
The largest stress a material can withstand before breaking
