Chapter 11 Flashcards
Define density
The mass per unit volume of a substance
How can you measure the density of a regular object?
- Measure mass using a top pan balance
- Measure dimensions using vernier calipers or micrometer and calculate volume with appropriate equation
How can you measure the density of a liquid?
- Measure mass of empty measuring cylinder, and pour some liquid into it and measure the volume directly. Use as much liquid as possible to reduce % error
How can you measure the density of an irregular object?
- Measure the mass of the object
- Immerse object on a thread in liquid in a measuring cylinder. Change in liquid level = volume
What is an alloy?
A mixture of 2 or more metals
State Hooke’s law
The force needed to stretch a spring is directly proportional to the extension of the spring from its natural length until it exceeds its limit of proportionality
What type of energy is stored in a stretched spring?
Elastic potential energy
What is deformation that stretches an object called?
Tensile
What is deformation that compresses an object called?
Compressive
What is a brittle material?
A material that snaps without any noticeable yield e.g glass
What is a ductile material?
A material that can be drawn into a wire e.g copper
How can you measure the stiffness of a material?
By using the gradient of a stress-strain line which = YM
What is the strength of a material?
The maximum tensile stress
In loading and unloading, what is permanent extension?
When the material has reached its limit of proportionality, and the unloading values are greater than the loading values due to the string stretching
On a graph, how can you see the work done to stretch a rubber band?
The area under the loading curve
