Energy Stores And Processes

Question 1

What are the 7 energy stores?

Answer 1

• thermal
• kinetic (KE)
• gravitational (GPE)
• chemical
• elastic
• nuclear
• electrical

Question 2

What are the 4 ways of transferring energy?

Answer 2

• heating (e.g. conduction)
• waves (e.g. sound)
• electric current
• force (e.g. friction)

Question 3

What is a system?

Answer 3

A system is an object/group of objects in which electricity is transferred between them.

Question 4

What is work done?

Answer 4

Energy transferred

Question 5

What are the two main types of work done?

Answer 5

Heating - energy stored thermally

Mechanical - work done against a force

Question 6

What are the units for work done?

Answer 6

Joules - same as energy

Question 7

What equation links work done, force and distance?

Answer 7

Work done = force x distance

W = F x s or Fs

Question 8

What is the equation to find kinetic energy?

Answer 8

Kinetic energy = mass x velocity squared / 2

Ek = mv^2 / 2

Question 9

What is kinetic energy?

Answer 9

Kinetic energy can be described as the movement of an object/objects

Question 10

What is gravitational potential energy (GPE)?

Answer 10

Energy is in the gravitational potential store when an object moves in relation to its position in a gravitational field

Question 11

How do we calculate GPE?

Answer 11

Work done = mass x gravitational field strength

W = mg

Question 12

How do we calculate a change in the GPE store?

Answer 12

GPE = mass x gravitational field strength x (change in) height
Ep = mgh

Question 13

What is the law of conservation of energy?

Answer 13

Energy can never be created or destroyed, only transferred usefully or dissipated to the surroundings

Question 14

How are GPE and KE linked?

Answer 14

GPE lost = KE gained. In other words, when an object falls it has less GPE but gains KE as it falls

Question 15

What is specific heat capacity (SHC)?

Answer 15

SHC (measured in J/kg *C) is the amount of energy required to heat 1 kilogram of a given substance by one degree Celsius. Unless otherwise stated, ignore the energy that is lost through dissipation

Question 16

What is power?

Answer 16

Power is defined as the rate at which energy is transferred or the rate at which work is done

Question 17

What equation links power, work done and time?

Answer 17

Power = work done / time taken
P = E / t

Question 18

What is the equation for efficiency?

Answer 18

Efficiency = useful output energy/total output energy

There is no symbol equation for efficiency

Question 19

What is elasticity and plasticity?

Answer 19

Elasticity is identifiable by an ability to return to its original shape after deformation
Plasticity is identifiable by a (somewhat) inability to return to its original shape.

Question 20

What is Hooke’s Law?

Answer 20

The extension of an elastic object (e.g. spring) is directly proportional to the force applied, provided the limit of proportionality is not exceeded

Question 21

What equation links force, spring constant and extension?

Answer 21

Force applied = sprint constant x extension

Question 22

How do we calculate the elastic potential energy store?

Answer 22

EPE = 1/2 x spring constant x extension squared
Ee = ke^2 / 2