Energy stores and transfers

Question 1

How can energy be transferred?

Answer 1

Via heating, waves, electricity or forces(Mechanical work)

Question 2

what is the definition of a system?

Answer 2

A system is an object/group of objects

Question 3

What is the definition of a closed system?

Answer 3

A closed system is one where no energy can escape to, or enter from the surroundings. The total energy in a closed system never changes

Question 4

True/false energy can’t be destroyed

Answer 4

True energy can’t be destroyed it can only be transferred usefully, stored or dissipated

Question 5

What are techniques that reduce unwanted energy transfer?

Answer 5

Lubrication reduces unwanted energy transfer via friction
streamlining reduces energy wasted due to air resistance or drag in water

Question 6

What is the definition of efficiency?

Answer 6

Efficiency is a measure of how much energy is usefully transferred

Question 6

What are the formulas for efficiency

Answer 6

1.Efficiency =Useful output energy transfer(J)/total input energy transfer(J)
2.Efficiency =Useful power output(W)/Total power input(W)

Question 7

Define kinetic energy store

Answer 7

Energy an object has because it is moving

Question 8

define gravitational potential store

Answer 8

Energy an object has because of its height above the ground

Question 9

Define elastic potential store

Answer 9

Energy an elastic object has when it is stretched/compressed

Question 9

Define chemical energy store

Answer 9

Energy that can be transferred by chemical reactions involving foods, fuels, and the chemicals in batteries

Question 10

Define thermal energy store

Answer 10

Energy an object has because of its temperature