Unit B - Physics Flashcards
How would you determine the average speed of a given object?
Average speed = distance travelled/time elapsed
V = d (final) - d (initial)/t (final) - t(initial)
What is the difference between a scalar quantity and a vector quantity?
A scalar quantity only indicates the magnitude of the quantity, whereas a vector quantity indicates both magnitude and direction.
Describe uniform motion
Uniform motion is a term used to describe an object that is traveling at a constant rate of motion in a straight line.
Describe the X axis method of plotting a graph
- up and right are positive
* down and left are negative
Describe the navigator method of plotting a graph
- North and east are positive
* South and west are negative
What is the formula for average velocity?
Average velocity = displacement/time elapsed
Difference between distance and displacement
Distance is a scalar quantity whereas displacement is a vector quantity.
List two ways that positive acceleration can occur
Positive acceleration can occur when the change in both the magnitude of the velocity and the direction are positive or when the change in both the magnitude of the velocity and the direction are negative.
List two ways that negative acceleration can occur
Negative acceleration occurs when the change in the magnitude of the velocity is negative while the direction is positive or when the change in the magnitude of the velocity is positive and the direction is negative.
What is the formula for analyzing accelerated motion?
Acceleration = change in velocity/time interval
v(f) - v(i)/t(f) - t(i)
What is force?
Force is defined as a push or a pull on an object, it is measured in newtons.
What happens when an unbalanced force is applied to an object?
When an unbalanced force is applied to an object, the object will gain or lose energy which in turn leads to a change in motion.
Define “work” in a physics context
Whenever a force moves an object through a distance that is in the direction of the force, work is done on the object.
What is the formula to find the amount of work done on an object?
Work = force x distance
W = Fd
Measured in joules (J)
Three conditions for work to be done on an object.
- there must be movement
- there must be a force
- The force and the distance the object travels must be in the same direction
Define chemical energy
Chemical energy is the potential energy stored in the chemical bonds of compounds.
Define electrical energy
Electrical energy is the work done by moving charges.
Define nuclear energy
Nuclear energy is the potential energy stored in the nucleus of an atom.
Define solar energy
Solar energy is energy from the sun. This energy travels to Earth as electromagnetic radiation.
Define kinetic energy
Kinetic energy is flowing water, wind, or any object in motion that could be made to do work because of its motion.
Define gravitational potential energy
Gravitational potential energy is the potential for an object to do work because of its position above the Earth’s surface.
Define mechanical energy
Mechanical energy is the sum of kinetic energy and gravitational potential energy
Gravitational potential energy equation
Ep(grav) = mgh
Or
Ep(grav) = Fd
Define elastic potential energy
Elastic potential energy is energy in which force can be applied against an opposing force resulting in a change in potential energy.
Kinetic energy formula
Kinetic energy = 1/2 (mass) (speed)^2
Ek = 1/2mv^2
Mechanical energy formula
Mechanical energy = kinetic energy + potential energy
Law of conservation of energy
The law of conservation of energy states that the total amount of energy in a given situation remains constant. Energy can be converted from one form to another but the total amount of energy never changes.
Evidence of energy conversions
- motion
- change in position
- change in shape
- change in temperature
Define an open system
Exchanges both matter and energy with its surroundings
Define a closed system
Cannot exchange matter but can exchange energy with its surroundings.
Define an isolated system
Cannot exchange either matter or energy with its surroundings
First Law of Thermodynamics
Total energy, including heat, in a system and its surroundings remains constant.
Second Law of Thermodynamics
Heat flows naturally from a hot object to a cold object, but never naturally from a cold object to a hot object.
Heat engine vs. Heat pump
Heat engine follows law of thermodynamics, motion of heat going from hot to cold is harnessed as kinetic energy. Heat pump requires energy to move heat from a cold area to a hot area.
Gunpowder engine
- Successful reciprocating pump needed force to drive piston forward and force to pull it back
- Gases generated by an explosion inside the engine drove a piston forward into a cylinder.
- Engine never developed due to safety hazards and no mechanism to pull the piston back
The heat engine
- The heat engine used heat to create steam to do work
* The heat engine was never created because they could not make the large drum in which the water was to be heated
The Savery engine
- first successful steam powered pump used to pump water out of mines
- could lift water to a height of only 6 m
The Newcomen engine
- A boiler produced steam that forced a piston up a cylinder. When cold water was sprayed on outside of cylinder, steam would condense and piston would move back down cylinder.
- cycle of heating and cooling the cylinder was inefficient and engine required tremendous amounts of heat to function.
The Watt engine
- Engine run on steam where boiler cylinder always remained hot and had a separate condenser to cool steam. Three times more effective than Newcomen engine
- steam engines were very large, therefore they could not replace horse-drawn carriages
The internal combustion engine
• petroleum fueled internal combustion engine used gasoline instead of coal gas, like other internal combustion engines. This engine was small enough to power road vehicles.
What is the formula for efficiency?
Efficiency = useful work output/useful work input
Formula for percent efficiency of mechanical energy
Percent efficiency = useful mechanical energy (work output)/total mechanical energy (work input) x 100%
Formula for the percent efficiency of thermal energy
Percent efficiency = heat (useful output)/heat (total input) x 100%
Name five solar energy sources
Solar radiation, wind energy, water energy, biomass, fossil fuels.
Name three non-solar energy sources
Geothermal energy, nuclear energy, and tidal energy.
What is the difference between a renewable energy source and a non-renewable energy source?
A renewable energy source is one that is continually and infinitely available, whereas a non-renewable energy source is limited and irreplaceable
Define cogeneration
Cogeneration is the process of using waste energy from one process to power a second process.
Define sustainable development
Sustainable development is economic development that meets current needs without compromising the ability of future generations to meet their needs.
