ENERGY CHANGES IN A SYSTEM

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Cards (25)

kinetic : moving objects have energy
gravitational : objects that are above the ground
elastic : objects that have been stretched or compressed will return to their original shape and size
magnetic : objects that have a magnetic store
elastic : objects have energy in their elastic potential store if they are stretched, squashed
electrostatic : objects with charge like electrons and protons interacting with one another have energy in their electrostatic state
chemical : chemical reactions transfer energy into or away from a substance's chemical store
nuclear : atomic nuclei release energy from their nuclear store during nuclear reactions
thermal : all objects have energy in their thermal store, the hotter the object the more energy it has in its store
a system is an object or group of objects
energy cannot be created or destroyed ➡️ energy can be transferred from one form to another
specific heat capacity is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree
when there is a change in the system, energy is transferred
power is defined as the rate at which energy is transferred or the rate at which work is done
the unit for power is watts (W)
an energy transfer of 1 joule per second is equal to a power of 1 watt
when energy transfers occur that are not useful these are described as energy bring dissipated to its surroundings
the amount of friction can be reduced by lubrication
insulation can prevent heat dissipating
good insulators must have low thermal conductivity and the layers should be as thick as possible
fibreglass makes a good insulator at home because air is trapped between the fibres
can reduce friction by adding bearings to prevent components from directly rubbing against on another
to reduce electrical resistance, use components with less resistance or lower the current
air resistance can be reduced by streamline shapes
sound can be reduced by tightening loose parts to prevent vibrations or lubricating parts