Materials Flashcards
How do you work out the density of a liquid?
- Measure the mass of an empty measuring cylinder.
- Pour some liquid in till the cylinder is nearly full (to reduce percentage error).
- Note the volume, and now measure the combined mass of the cylinder and liquid. You can now calculate the mass of the liquid.
- Density = Mass/Volume.
How do you work out the density of an irregular solid?
- Measure the mass.
- Immerse the object in a measuring cylinder, and note the increase in volume. This increase is the volume of the object.
- Density = Mass/Volume.
What is Hooke’s Law?
- Hooke’s Law states that the force needed to strecth a spring is directly proportional to the extension of the spring from it’s natural length.
- (F = kΔL).
Describe how springs in parallel and in series act differently.
- For springs in parallel the effective spring constant is all other spring constants added together, like resistors in series ( K = K1 + K2 + … ).
- For springs in series the effective spring constant is always less than the individual spring constants, like resistors in parallel ( 1/K = 1/K1+ 1/K2 + … ).
How do we show the energy stored in a stretch spring?
We plot a graph of force applied on the y and extension on the x. The area under the graph (i.e. 1/2 X FΔL) is equal to energy stored.
Define Tensile Stress and give its unit.
Tensile Stress is the tension in a wire divided by the cross sectional area of the wire (F/A). It is measured in Pascals or N/m^2.
Define Tensile Strain.
Tensile Strain is the extension of a wire divided by it’s original length (ΔL/L). As it is a ratio is has no unit.
What is the Young modulus?
A measure of stiffness which is equal to Tensile Stress / Tensile Strain.
How do you work out the density of a regular solid?
- Measure it’s mass using a top pan balance.
- Measure it’s dimensions using vernier callipers or a micrometer so you can work out it’s volume using an appropriate formula.
- Density = Mass/Volume.
