Physics Module 3 Flashcards
What is pressure, and its formula (for solids)?
Force per unit of area
p = F/A
What is different about pressure from fluids?
Fluids (liquid and gas) constantly generate pressure from molecules banging into their surroundings
What are three properties of pressure in fluids?
- Acts in all directions
- Increases with depth
- Depends on density of fluid
What is the formula for pressure in fluids?
Pressure = density x gravity x depth
P = pgh
What is unique about pressure in gases?
They can be compressed (atmosphere denser at lower levels)
What is the unit for standard atmospheric pressure, and what is its equivalent in pascals?
atm (atmosphere) – 1atm = 100,000 Pa
For pressure in gas, what two factors are linked with pressure?
Volume and temperature. A change in one causes a change in at least one other.
What happens to pressure in gas when temperature rises, and why?
Pressure rises because since particles have more energy, there are more collisions with more force.
What happens to pressure in gas when volume decreases/density increases, and why?
Pressure rises because less space/more particles means more collisions.
What is Boyle’s Law?
For a fixed gas at constant temperature, the pressure is inversely proportional to the volume.
What is the difference between elastic and inelastic (plastic) objetcs?
- Elastic objects go back to their original shape after being stretched/compressed
- Inelastic objects keep their new shape
What does it mean if an object has been deformed?
It has permanently changed shape.
What is extension, and what is its formula?
Extension (x) is the increase in length of a spring when stretched. F = kx
What is the spring constant?
Spring constant (k) of an object is how many Newtons it would take to stretch the object by 1m. Higher k = stiffer the object. Constant of load/extension
What is Hooke’s Law?
Below the elastic limit, extension is proportional to load
What is the elastic limit?
The point at which an elastic object has been stretched/compressed so much it is no longer elastic, and will not return to its original shape. (Extension and load no longer proportional).
What are the two definitions of Power, and their formulas?
- The rate at which energy is transferred (P = E/t)
- The rate at which work is done (P = W/t)
What is ‘work done’, and its formula?
The force used to move an object a certain distance (W = F x d)
What is the unit for power, and the unit for energy/work done?
- Power – Watts (W)
- Energy/work done – Joules (J)
What are the eight different ways energy can be stored?
- Kinetic energy
- Gravitational potential energy
- Elastic (strain) energy
- Chemical energy
- Electrostatic energy
- Nuclear energy
- Thermal energy
- Magnetic energy
What are energy pathways?
Ways in which energy can be transferred.
What are the four ways energy can be transferred?
Mechanically (force moving something), electrically, heating, radiation
What is the law of conservation of energy?
Energy can be stored or transferred, but it cannot be created or destroyed.
What happens whenever work is done?
Energy is transferred.
What is the formula for calculating the gravitational potential energy of an object?
Potential energy = mass x gravity x height
PE = mgh
What is the formula for calculating the kinetic energy of an object?
Kinetic energy = 1/2 mass x velocity(squared)
KE = 1/2mv(2)
Is energy a scalar or a vector?
Scalar
How is efficiency calculated?
- Efficiency = useful power output/total power input
What is the rate at which an engine gets work done?
Power (work done/time)
How do you calculate useful power output?
force x speed
What is the difference between renewable and non-renewable fuels?
- Renewable fuels can be replaced and will never run out
- Non-renewable fuels are limited and will one day run out
What are examples of non-renewable fuels?
- Coal
- Oil
- Natural gas
- Nuclear fuels
What are examples of renewable fuels?
- Hydroelectric energy
- Tidal energy
- Wind energy
- Wave energy
- Geothermal energy
- Solar energy
- Biofuels
