Energy stores and systems

What is a system ?

An object or a group of objects

What is a closed system ?

One where no energy can enter or escape from the surroundings. The total energy in a closed system never changes.

Name the 8 energy stores with their definitions

Kinetic energy - Energy an object has when its moving

Elastic energy - energy an object has when its stretched or compressed

Gravitational potential enegry - Energy an object has because of its height above the ground

Magnetic energy - energy a magnetic object has when near a magnet or in a magnetic field

Thermal energy - energy a object has when its heated

Chemical energy - energy that can be transferred in chemical reactions involving food, fuels and batteries

Nucleur - energy stored in the nucleus of the atom

electrostatic - energy a charged object has when near another charged object

What are the four energy transfers

radiation

heating

electrically

mechanically

What is specific heat capacity ?

The amount of energy required to raise the temperature of 1kg of a substance by 1 degrees.

Required practical one : :

• place a beaker on a balance and press 0

• Now place your substance in the beaker to measure its mass

• Place a thermometer and immersion heater into the substance allowing you to read the starting temperature of the substance

• Wrap insulating foam around the beaker to stop the thermal energy transfer to the surroundings

• connect a joulemeter to the immersion heater. Telling you how many joules of electrical energy passes into the immersion heater

• Now time for 30mins allowing the temperature to rise enough for you to accurately to read off the thermometer

• Read the total number of joules that passed into the immersion heater and the final temp.

• You now use all of this info to calculate the SHC of the substance.

Safety precautions -

• Dont handle block whilst heating

• keep block on a heatproof mat

What is power ?

The amount of energy transferred per second

What does 1 watt equal to ?

1 joule of energy transferred per second