Chapter 1 Flashcards
Energy stores
- Gravitational potential energy
- Kinetic energy
- Elastic potential energy
- Thermal (heat) energy
4 types of potential
- Electric potential
- Magnetic potential
- Chemical potential
- Nuclear potential
Physical processes
- Mechanical (forces, sound waves)
- Electric current
- Electromagnetic waves
- (Heating)
Energy transfers eventually the energy is…
Dissipated
Energy store of a pendulum
GPE → KE → GPE
Energy store of a car at constant speed
Chemical → thermal energy
Energy store of a car braking
Kinetic → thermal energy
What is work done?
The energy transferred by a force.
How to measure work done?
Work done = force x distance
What is work done measured in?
J
What is force measured in?
N
1 Joule =
1 Newton metre
How to measure Gravitational Potential Energy?
GPE = mass x grav. field strength x height (E = m x g x h)
How to measure Kinetic Energy?
KE = 0.5 x mass x velocity2
(E = 0.5 x m x v2)
How to measure Elastic Potential Energy?
E = 0.5 x spring constant x extension2
(E = 0.5 x k x e2)
How to measure Thermal Energy?
Energy = mass x s.h.c x temp change
Sankey diagrams
A way of showing the efficiency of a device.
Arrows of a sankey diagrams
The thickness of each arrow is drawn to scale to show the amount of energy
How to measure efficiency?
Efficiency (%) = useful energy output x 100
——————————————
total energy input
How efficient is a device?
The closer the efficiency is to 1 or 100%, the more efficient the device is and the less energy it wastes
Energy transferred
Power x Time
(Power) Work done
Power x Time
