Phy1 - Energy Flashcards
What is a system?
A group of objects
What are the 4 ways energy can be transferred?
1) Mechanically (a force moving
2) Heating
3) Electrically (charge being transferred)
4) Radiation
What is “work done” the same as?
Energy transferred
What is the unit for work done?
Joules (J)
What is the equation for kinetic energy?
Ek = ½ × m × v²
Kinetic energy = 0.5 × mass × velocity²
What are the 8 energy stores?
- Thermal
- Kinetic
- Gravitational Potential
- Elastic Potential
- Chemical
- Magnetic
- Electrostatic
- Nuclear
What is a closed system?
A system where matter or energy cannot enter or leave
Describe the energy changes in a falling ball
The ball’s gravitational potential energy would decrease as it came closer to the ground.
The ball’s kinetic energy would increase as it speeds up
What is specific heat capacity?
The amount of energy needed to increase 1kg of a substance by 1⁰C
What is the equation for power?
P = E ÷ T
Power = Energy transferred ÷ time
or
P = WD ÷ T
Power = Work Done ÷ time
Name the energy store in a streched or compressed spring
Elastic potential energy
What does “conservation of energy” mean?
Energy can be stored, transferred or dissipated. It can never be created or destroyed
Describe the energy transfer involved in a person lifting a weight
• The person’s chemical energy
store decreases
• The kinetic energy store of the
person’s arm and the weight
increases.
• The gravitational potential
energy store of the person’s
arm and the weight increases
A book on the top shelf has a
gravitational potential energy
store of 100 J. The book falls. How
much energy will be in the book’s
kinetic energy store as it hits the
ground?
100 J
What is another name for “wasted energy?”
Dissipated energy