8) Energy- Forces Doing Work Flashcards
What is the conservation of energy?
Energy vannot be created or destroyed, only transferred from one store of energy to another
How can energy be transferred between stores?
Electrical Work
Heating
Mechanical Work
Waves (light etc.)
How does electrical work transfer energy?
An electrical current transfers energy from one object to another
What is an example of electrical work transferring energy?
A battery powering a torch
How does heating transfer energy?
Heating an object transfers energy to its interal store
What is an internal store?
The sum of the energy in the kinetic and chemical stores of its particles
What is mechanical work in transferring energy?
Energy transferred from one object to another via a force is mechanical work
What is an example of mechanical work transferring energy?
When you push a wheelchair, energy is transferred to the kinetic store of the wheelchair
What is mechanical work?
The work done by a force equal to the energy transferred to the object
How do you increase work done?
Pushing with the same force for longer
Pushing with a larger force for the same distance
How is work done calculated?
Work done = force x distance
How is electrical work calculated?
Electrical work = potential difference x current x time
E = V x I x t
What is power?
Power is the rate of energy transfer (or work done)
What is power measured in?
Watts (W)
How is power calculated?
Power = work done / time
