Mechanical Energy Transfer and Conservation of Energy

Question 1

how do forces cause mechanical energy to transfer?

Answer 1

• work done is the same as energy transferred
• energy is transferred mechanically when a force moves an object

Question 2

what’s an example of forces causing mechanical energy to transfer?

Answer 2

• a ball thrown into the air, it is thrown upwards with force
• the chemical energy store of your arm too the kinetic energy stores of the ball and arm

Question 3

what’s another example of forces causing mechanical energy to transfer?

Answer 3

• a car slowing down, friction acts between the car’s brakes and wheels
• the wheel’s kinetic energy stores to the thermal energy store of the surroundings

Question 4

what is movement?

Answer 4

energy in an object’s kinetic energy store

Question 5

how is energy transferred to and away from the kinetic energy store?

Answer 5

transferred when an object speeds up, then away when an object slows down

Question 6

what is the formula for finding the energy in an object’s kinetic energy store?

Answer 6

Ek = 1/2 x m x v2
.- Kinetic energy (J)
- Mass (kg)
- (Speed)3 (m/s)2

Question 7

how can raised objects store energy in GPE store?

Answer 7

all objects raised above the ground gain energy in their GPE store

Question 8

what is the formula for finding the energy in an object’s GPE?

Answer 8

Ep = m x g x h
- g.p.e (J)
- Mass (kg)
- Gravitational Field Strength (N/kg)
- Height (m)

Question 9

how can stretching transfer energy to Elastic Potential Energy store?

Answer 9

stretching or squashing an object

Question 10

what is the formula for finding the energy in an object’s EPE?

Answer 10

Ee = 1/2 x k x e2
- EPE (J)
- Spring constant (N/m)
- (Extension)2 (m)2

Question 11

what happens when energy is transferred between stores?

Answer 11

• some energy is transferred to the store you want it in, this energy is usefully transferred
• in any transfer, energy is transferred to useless stores (disspiated), usually thermal energy stores
• this is described as ‘wasted’ energy

Question 12

what is the Conservation of Energy Principle?

Answer 12

• whenever a system changes, all the energy is moved between stores, it ever disappears, this is for every energy transfer
• even when energy is dissipated is isn’t gone, its just been transferred to an unwanted energy store

Question 13

how can you calculate energy transfers using conservation of energy?

Answer 13

• there are calculations for when energy is transferred between two stores
• the conservation of energy principle says that energy can’t be destroyed
• when theres no air resistance for a falling object:
  Energy lost from the g.p.e store = Energy gained in the kinetic energy store