P1:Energy Flashcards
When energy is transferred to an object, the energy is….
Stored in one of the object’s energy stores e.g. kinetic energy store etc.
Kinetic energy is…
Anything moving
Thermal energy is…
The hotter the object, the more thermal energy
Chemical energy is…Example?
Anything that can release energy by a chemical reaction e.g. Food
Gravitational potential is…
Any object raised above ground level
Elastic potential is…Example?
Anything stretched e.g. springs, rubber bands
Example of electrostatic energy…
Two charges that attract or repel eachother
Example of magnetic energy…
E.g. Two magnets that attract or repel each other.
Nuclear energy is…
The nucleus of an atom releases energy from this store in nuclear reactions
4 ways energy can be transferred:
Mechanically, Electrically, By radiation, By heating.
Mechanically transferred energy happens when…
A force does work.
Electrically energy transferred happens when…
When a moving charge does work.
Energy can be transferred by heating - this is when…
Energy is transferred from a hotter object to a colder object.
Energy can be transferred by radiation - this is when…
Energy is transferred by e.g. Sound or light.
When a system changes…It can be transferred…
Energy is transferred. It can be transferred into or away from the system between different objects in the system or between different types of energy stores.
What is a system?
A single object or group of objects that your interested in.
What are closed systems?What is the net change like?
Where no matter or energy can enter or leave. The net change in the total energy of a closed system is always zero.
When a closed system changes…
There is no overall change in the total energy of the system.
Conservation of Energy Principle:
Energy can be transferred usefully, stored or dissipated but can never be created or destroyed.
When a system changes…
The energy is simply MOVED between stores. (Never disappears)
Is energy that is dissipated/wasted gone ?
No. It has just been transferred to an energy store that we didn’t want.
What causes mechanical energy transfers?
Forces.
2 points about Work Done:
- if a force moves an object, then work is done.- work done is the same as energy transferred.
What is the energy in an objects Kinetic Energy Store?The energy in the Kinetic Energy Store depends on…
Movement.The object’s mass and speed - the greater its mass and the faster it’s going, the more energy in the Kinetic Energy Store.
When an object speeds up, what happens to the energy?
It is transferred to the kinetic energy store.
Formulae for finding object’s kinetic energy store:Units?
E = 1/2 x mass x speed (v) squared.Mass units - kgSpeed units - Minuites / secondsEnergy - joules
Formulae to find Gravitation Potential energy:Units?
E = Mass X gravitation field strength (9.8n/kg) x heigh Mass unit - kgHeight unit - m
Energy lost from the gravitation potential store = ?
Energy gained in the kinetic energy store (this is for a falling object when there’s no air resistance)
Formulae to find elastic potential energy store:
E = 1/2 x Spring constant x extension squared.Spring constant unit - n/mExtension unit - m
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1kg by 1 c. Basically, how hard it is to heat something up - some materials need more energy to be transferred to their thermal energy stores in order for their temperatures to increase.
The amount of energy stored or released as a material changes temperature depends on…
The specific heat capacity of the material.
Formulae for change in thermal energy:
= mass x specific heat capacity x temperature change.
Give the 9 steps to investigating the specific heat capacity of a SOLID BLOCK:
1) measure the mass of the block.2) wrap it in an insulating layer to reduce energy losses (e.g. thick newspaper)3) set up the apparatus. (connect ammeter and power supply to the insulation)4) measure the starting temperature of the block.5) turn on the power supply and start a stopwatch.6) record potential difference of the power supply and the current - they shouldn’t change.7) after 10mins take a reading of the block’s temprature.8) turn of the heater and work out the temprature change.9) work out the power using the equation.
What 3 things do you need before measuring specific heat capacity?
1) calculate the power.2) calculate the energy transferred.3) find the change in temperature.CALCULATE.
What is POWER?
The rate of energy transfer - the rate of doing work. Power is how fast energy is transferred.
What is power measured in?
Watts.
One WATT =
1 joule of energy transferred per second.
Give the 2 equations you can use to calculate power:
1 POWER = ENERGY TRANSFERRED DIVIDED BY TIME.2POWER = WORK DONE DIVIDED BY TIME.
Explain how USEFUL energy is formed:
When energy is transferred between stores, some energy is transferred to the stores you want it in. USEFULLY TRANSFERRED.