P1 Flashcards
What is energy stored in?
Energy stores
How is energy transferred?
Heating, waves, an electric current or by a force when it moves an object
Describe the energy store changes when an object falls and gains speed?
It’s store of gravitational potential energy decreases and its kinetic energy store increases
What happens to a falling objects energy as its kinetic energy store decreases?
Some or all of its energy is transferred to the sorroundings. The thermal energy store of the sorroundings increases and energy is also transferred by sound waves
What are the 5 types of energy store?
Chemical
Kinetic
Gravitational potential
Elastic potential
Thermal
What is chemical energy?
Fuels, foods or chemicals found in batteries
What is kinetic energy?
The energy of an object has because it is moving
What is gravitational potential energy?
The energy stored in an object because of its position, such as an object above the ground
What is elastic potential energy?
The energy stored in a springy object when you stretch or squash it
What is thermal energy?
The energy a substance has because of its temperature
What is the conservation of energy?
Energy cannot be created nor destroyed
Does conservation of energy apply to all energy changes?
Yes
What is a closed system?
A system in which no energy transfers take place out of or into the energy stored of the system
Can energy be transferred between energy stores within a closed system?
Yes
What is the total energy of the system before and after any transfers?
The same
What is work done?
Amount of energy required to do something/ transferring energy
What is the work done equation with units?
Work done(Joules)= Force(N) X distance(cm)
What is the relationship between energy transferred and work done?
They are equal
What is work done to overcome friction?
Transferred as energy to the thermal energy stored of the objects that run together and to the sorroundings
What is gravitational potential energy?
How much higher or lower you are than sea level
What is the gravitational potential energy with units?
Gpe(joules)= mass(kg) X gravitational field strength(N/kg) X height(m)
What is the value of gravity atop Al field strength always on earth?
9.8N/kg
What is the weight equation with units?
Weight= Mass X gravitational field strength
What is the change in an objects GPE store equation with units?
GPE(joules)= weight(N) X change of height(m)
Is the gravitational attraction the surface of the moon more or less than earths surface?
Less
What is the kinetic energy equation with units?
Kinetic energy( joules) = 0.5 X mass(kg) X speed squared( m/s squared)
What does the energy in the kinetic energy store of a moving object depend on?
It’s mass and speed
What is elastic potential energy?
The energy stored in an elastic object when work is done on the object
What is the elastic potential energy equation with units?
Elastic potential energy(joules) = 0.5 X spring constant( N/m) X extension squared( m squared)
What is useful energy?
The energy in the place we want it and in the form we need it
What is wasted energy?
The energy that is not useful energy and is transferred by a undesired pathway
What happens to wasted energy?
Transferred to the surroundings which become warmer
What happens as energy dissipates?
It gets less and less useful
In simple terms, what does dissipates mean?
How things loose energy/ spreads out
What is the efficiency equation?
Efficiency= (usefull energy transferred divided by energy supplied to appliance) X 100
What can no energy transfer be more than?
100%
How do machines waste energy?
Friction between their moving parts, air resistance, electrical resistance and noise
How can machines be made more efficient?
By reducing the energy they waste eg lucbrication is used to reduce friction between moving parts.
What is the maximum efficiency?
1 or 100%
What supplies most of the energy used in a home?
Electricity and gas and/ or oil
What form of energy does electrical appliances transfer energy in?
Useful
What is power?
The rate of transfer of energy
What is the power equation with units?
Power(watts) = Energy transferred to appliance(joules) divided by time taken( seconds)
What is the efficiency equation?
Efficiency= (useful power out divided by total power in) X 100
What is the power wasted equation?
Power wasted= total power in - useful power out
