Physics 1 Flashcards
What is key about energy?
Energy cannot be created or destroyed. It can only be TRANSFERRED from one store to another.
What are the 8 energy stores?
Kinetic, Chemical, Thermal, Elastic Potential, Gravitional Potential, Electrostatic, Nuclear Magnetic, (You can merge magnetic and electrostatic to make electromagnetic)
What are the pathways?
- Mechanical
- Heating
- Electrical
- Work done by force
When energy is transferred, almost always some of the energy is transferred to the ______________ energy store of the surroundings.
-Thermal energy store
How can energy be transferred?
Energy can be transferred mechanically, elastically, heating or by radiation.
When a force makes things change it _____________________.
It mechanically transfers energy between different energy stores.
What does friction do?
Friction transfers energy mechanically into the thermal energy of the object or the surroundings.
What pathway is affected by weight?
-The mechanical pathway.
What is another word for a mechanical energy transfer pathway?
-Work
What is work?
Work is the energy transferred, when a force moves an object through an distance.
What is the formula for work done?
W=fs
What does W=fs stand for?
Work done= Force x distance moved in the direction of the force.
What are the units for W=fs?
W = f x s
Joules (J)= Newtons (N) x Distance moved in metres (m)
What is the formula for Gravtional Energy store?
Ep=mgh
What does Ep=mgh stand for?
Ep=mgh
Energy potential= Mass x gravitational field strength x height
What are the units for Ep=mgh?
Ep=mgh
Joules (J)= Mass (kg) x 9.8 (n/kg) x height (m)
What energy store is the energy from the elastic store transferred to the most?
-The gravitational energy store
What is the formula for the elastic potential store?
Ep = 1/2 k x e².
When is energy transferred to the elastic potential energy store?
Energy is transferred when a spring is stretched or compressed.
Work done = _______ potential energy
Work done = Elastic potential energy ( as long as the limit of proportionality is not exceeded.)
What are the units for Ep= 1/2 k x e²?
Joules= 1/2 x n/m x extension (m)
If extension isn’t in metres, than convert to metres
What does Ep = 1/2 k x e². stand for?
Elastic potential energy = 0.5 x spring constant x extension²
What is power?
Power is the rate of energy transfer. It is how much energy is transferred by second.
What is the formula for power?
P= w/t , Power= work done divided by time
What is the unit of power?
Watts (W), One watt is one joule per second.
1w= 1 joule per second.
What is the formula for Efficiency?
Efficiency= (useful energy out ÷ total energy in) X100
What is the unit for efficiency?
Percent %
