All sections Flashcards
What is motion?
It occurs when an imaginary line joining the object to the reference point changes in length, direction, or both.
What is uniform motion?
It describes an object that is travelling at a constant rate of motion in a straight line. This includes uniform acceleration.
What is average speed? What is the formula and what do the letters represent?
It is uniform motion that involves travelling a distance in a specified time.
Formula: v= Δd/Δt
v: average speed (m/s)
d: distance travelled (m)
t: time elapsed (s)
How is average speed represented in a graph?
time t (s): x axis
distance d (m): y axis
called a distance-time graph
slope: speed
Describe a speed-time graph
time t (s): x axis
speed v (m/s): y axis
- a horizontal line means uniform motion
- finding the area below the line gives you the distance travelled
What is velocity? What is the average velocity formula?
It describes both the rate of motion and the direction of an object.
Formula
->v = Δ->d/Δt
arrow on v: average velocity (m/s (direction))
arrow on d: displacement (m (direction))
t: time elapsed (s)
What is a scalar quantity? What is a vector quantity?
A scalar quantity indicates “how much” (the magnitude) of the quantity. A vector indicates the magnitude AND the direction of the quantity. An arrow gets added above a symbol to demonstrate that it is a vector quantity.
What is displacement?
It is like distance, but instead is a vector quantity (also shows direction) that the movement occurs in. It is a measurement of the distance AND the direction change in position of an object from a reference point.
Describe a position-time graph.
time t (s): x axis
position d(with arrow) (m): y axis
velocity: slope
Describe a velocity-time graph.
time t (s): x axis
velocity v (m/s) (direction): y axis
Area under line is displacement/position
slope: acceleration
What is acceleration? What is the formula?
A change in velocity during a specific time interval. It is a vector quantity.
Formula
acceleration = change in velocity/change in time or time interval
acceleration: m/s2
Describe how positive/increasing acceleration occurs.
1) when the change in both the magnitude of the velocity and the direction are positive
2) when the change in both the magnitude of the velocity and the direction are negative
Describe how negative/decreasing acceleration occurs.
1) when the change in the magnitude of the velocity is negative while the direction is positive
2) when the change in the magnitude of the velocity is positive while the direction is negative
What is force? What is it measured in? What is the formula for force?
A push or pull on an object. When an object is at rest, all forced acting on it are balanced. It is measured in newtons.
Formula:
F= ma
(mass times acceleration) (kg times m/s2)
Is energy required to maintain uniform motion?
No
When is work done on an object? What is the formula for work?
When a force moves an object that is in the direction of the force, then work is done. It is measured in joules.
Formula
W=Fd
J= N x m = kg x m/s2 x m = kg x m2/s2
What are the three conditions for work to be done on an object?
1) there must be movement
2) there must be a force
3) the force and the distance the object travels must be in the same direction
What is energy?
Energy is the ability to do work. Work and energy are basically the same thing
E = W
What is chemical energy?
It is the potential energy stored in the chemical bonds of compounds. e.g. wood burning
What is electrical energy?
Work done by moving charges.
What did the volta pile prove?
It constituted the first battery, resulting in it providing evidence of a connection between chemical energy and electrical energy.
Is magnetism a form of energy?
yes
What are two forms of energy that can be produced from electricity?
Light and heat energy
What is nuclear energy? Explain nuclear fission and fusion.
Nuclear energy is the potential energy stored in the nucleus of an atom. When the nucleus of an atom is split (nuclear fission) or when the nuclei of two atoms combine (nuclear fusion), this energy is released.
What is kinetic energy?
Something doing work because of its MOTION.
What is gravitational potential energy?
An object raised above Earth’s surface that has the potential to do work because of its position.
What is mechanical energy?
It is the sum of the energy of motion and position.
What is thermodynamics?
The study of the interrelationships of heat, work, and energy.
What is heat?
The transfer of thermal energy from a hot object to a cold object.
Can an object have both potential and kinetic energy, or just one?
It can have both.
What is potential energy? What is the formula?
Potential energy has the potential to do work. It is energy that is stored or held in readiness.
Ep(grav) = mgh
m: mass (kg)
g: acceleration due to gravity (9.81m/s2)
h: height (m)
What is the formula for weight?
Mass times gravity
What is elastic potential energy?
This type of energy is stored in a stretched or compressed spring, a trampoline, a diving board, etc. The force is often used to stretch an elastic.
What is chemical potential energy?
The energy found in chemicals, stored in the bonds of chemical compounds. When a chemical reaction takes place and work is done, this potential energy is released.
What is the formula for kinetic energy?
Ek = 1/2 (m) (v2)
m: mass (kg)
v2: speed squared
What is the formula for kinetic energy?
Em = Ek + Ep
= 1/2mv2 + mgh
What is the law of conservation of energy? How does it relate to mechanical energy?
It 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. Thus, the total amount of mechanical energy remains constant.
True or false: potential energy = kinetic energy
True
Explain conversions of energy with a pendulum.
Name four pieces of evidence of energy conversion.
1) Motion
2) Change in position
3) Change in shape
4) Change in temperature
The _________-__________ nuclear fusion reaction that occurs at the centre of the sun releases tremendous amounts of solar energy that travels to Earth as ________________ waves.
Hydrogen-hydrogen, electromagnetic
Name two technological systems that convert energy. These are thermal power stations. What is a thermal power station?
- hydro-electric dams
- coal-burning power stations
A thermal power station creates heat to produce steam, which drives the turbines.
What is the CANDU?
The CANadian Deuterium Uranium reactor.
Solar cells and fuel cells operate like _____________.
Batteries
What is a system?
A set of interconnected parts.
What is a closed system? Give an example.
A system that cannot exchange matter but can exchange energy with its surroundings. e.g. closed can of soup
What is an isolated system?
A system that cannot exchange either matter or energy with its surroundings.
Describe how work and heat are different.
Work involves the movement of matter from one location to another, while heat is a transfer of thermal energy from one location to another.
Name two ways the energy of a system can be increased.
- heat can be added from its surroundings
- work can be done on a system by its surroundings
Name two ways the energy of a system can be decreased.
- heat can flow out of a system
- work can be done by a system on its surroundings
heat added to a system = _____________ energy + heat
mechanical
What are perpetual motion machines/perfect machines?
Machines that convert no energy into other forms of energy and operate indefinitely. Mechanical energy is completely conserves as mechanical energy.
What is the second law of thermodynamics?
It states that heat always flow naturally from a hot object to a cold object, but never naturally from cold to hot.
What is a heat engine? name an example.
It’s a device that converts heat into mechanical energy. However, only some of the input heat can be converted and the rest is expelled as exhaust heat.
e.g. a thermo-electric converter
What is a heat pump? Name an example.
A device that uses mechanical energy to transfer heat. E.g. refrigerators
Describe the Archimedes screw.
- A turbine and a hydraulic machine
- used as a water pump and raised water form low-lying bodies of water
- could not lift water very far because of the downward force of the water
Describe the Persian wheel.
- simple turbine machine used to pump water
- turned by animals, moving water, or wind
- sometimes used for irrigation
- could not lift water very far because of the downward force of the water
Describe the reciprocating pump.
- limited in height it could raise water (the atmospheric pressure can only push up to a height of 9m)
- uses backward and forward movement to move a fluid
- positive displacement pump
What is a steam engine?
Any machine that generates steam and converts the steam pressure into mechanical motion.
When you boil water, the resulting steam exerts pressure and moves objects.
Determine whether each of these machines use a piston.
Gunpowder engine
heat/papin engine
Savery engine
Newcomen engine
watt engine
internal combustion engine
otto engine
Hero engine
Gunpowder engine: yes
heat/papin engine: yes
Savery engine: no
Newcomen engine: yes
watt engine: yes
internal combustion engine: yes
otto engine: yes
hero engine: no
Almost every engine in the early 1900s was an _______ engine and it could produce the same amount of energy as a horse, or 1p (horsepower)
otto
In an internal combustion engine, energy is released by _____________ fuel, ignited by an __________ spark.
Burning, electrical
What is energy input?
The initial energy source.
What is useful energy output?
The energy needed to do work.
All energy is either waste energy or __________.
Work
What is useful work output?
The work a machine is supposed to do.
Systems with moving parts always lose some energy as _________.
heat
True or false: the efficiency of a system can be 100%
False
What is efficiency?
A measurement of how effectively a machine converts energy input into useful energy output.
What are the formulas for percent efficiency?
percent efficiency = useful mechanical energy output/total mechanical energy input x 100%
percent efficiency = work output/work input x 100%
percent efficiency = heat output/heat input x 100%
What is solar radiation? Is it renewable?
The radiant energy from the sun emitted by the hydrogen-hydrogen nuclear fusion reaction that occurs in the sun’s core. This is renewable energy.
Describe wind energy. Is it renewable? Is it a form of solar energy?
- the convection currents to due the unequal heating and cooling of earth
- can be used to move turbines
- caused by convection currents of air
- renewable
- indirect solar energy
Describe water energy. Is it renewable? Is it a form of solar energy?
- results when surface water is heated by the sun, which drives the hydrological cycle
- falling water can be used to move a turbine
- used in hydro-electric dams
- indirect solar energy
- renewable
Describe biomass energy. Is it renewable? Is it a form of solar energy?
- any form of organic matter that can be combusted to release chemical potential energy
- indirect solar energy
- renewable
Describe fossil fuels. Are they renewable? Is it a form of solar energy?
- formed from dead plants and animals and can be combusted to release energy
- oil, natural gas, coal
- indirect solar energy
- non-renewable
Describe nuclear energy. Is it renewable? Is it a form of solar energy?
- obtained from the conversion of mass to energy in either a fission or fusion reaction
- not solar energy
- non-renewable
Describe geothermal energy. Is it renewable? Is it a form of solar energy?
- thermal energy from the core of the earth
- only useful as a source of energy in active geological regions (hot springs, volcanoes)
- not solar energy
- renewable
Describe tidal energy. Is it renewable? Is it a form of solar energy?
- involves the movement of ocean water caused by the gravitational pull of the moon
- in areas where the difference between high tide and low tide is significant, the water can be used to produce electricity
- not solar energy
- renewable
What is a renewable energy source?
They are continually and infinitely available.
What is a non renewable energy source?
They are limited and irreplaceable.
What are the 3 factors that have placed dangerous demands on our energy supplies.
- amount of energy per person has increased
- world population is growing exponentially
- many societies now use non-renewable energy rather than renewable sources as their primary energy sources
What is exponential growth?
As a result of things like innovations in medicine, better public health, and technological innovations, the population has increased at an exponential rate.
Extraction/combustion of fossil fuels can:
(4 points)
- disrupt ecosystems
- spill oil
- release greenhouse gases
- release chemicals that contribute to acid rain
As energy use rises, fossil fuels will be __________.
Depleted
Until feasible alternative sources are developed, ___________ and improved __________ are key.
Conservation, efficiency
What is cogeneration?
The process of using waste energy from one process to power a second process .
