Forces And Energy Flashcards
What are the changes involved in the way energy is stored when systems change
Energy is transferred into or away from the system, between different objects in the system or between different type of energy stores
Some energy is dissipated and stored in less useful ways
What happens where there are energy transfer in a closed system
There is no net change to the total energy in that system
What are the different ways energy of a system can be changed thru work done
If a system e.g. a box is lifted up off the floor, as the box is lifted work is done Causes energy to be transferred to the box’s kinetic and GPE store
What are the different ways energy of a system can be changed thru heating
A pan of water is heated on a gas camping stove, when the system is the pan of water, energy is transferred into the system by heating to the thermal energy stores of the pan and water which increases their temp
What are the different ways energy of a system can be changed thru electrical equipment
An electric toothbrush is a system, it transfers energy electrically from the chemical energy store of its battery to the kinetic energy store of its bristles. Some of this energy is transferred out of the system to the surroundings by sound and heating
What is energy transferred equal to
Work done
How do u measure work done by a force
Work done = force x
What is work done measured in
Joules (J)
What is one watt equal to
One joule per second
What is power
The rate of energy transfer (W)
Or how much work is being done every second
When do mechanical processes become wasteful
When they cause a rise in temperature so dissipating energy in heating the surroundings
How do u calculate the changes in energy involved when a system is changed by work done by forces
What happens where they are energy transfers in a closed system
There is no net change to the total energy in that system
What happens in all system changes
Energy is dissipated so that it is stored in less useful ways
