Energy

Question 1

Name the 8 energy stores

Answer 1

kinetic, elastic potential, gravitational potential, thermal, chemical, nuclear, magnetic, electromagnetic

Question 2

Name the 4 energy transfers

Answer 2

mechanical, heating, electrical, radiation (sound/light)

Question 3

What is the kinetic energy equation?

Answer 3

1/2 m v squared
(m=mass in kg, v=velocity in m/s)

Question 4

What is the elastic potential equation?

Answer 4

1/2 k e squared
(k=spring stiffness in N/m, e=extension in m)

Question 5

What is the gravitational potential energy equation?

Answer 5

m g h
(m=mass in kg, g=gravitational field strength in N/kg (on Earth its 9.8), h=height in m)

Question 6

What is the specific heat capacity equation?

Answer 6

ΔE = m × c × Δθ
(ΔE=thermal energy change, m=mass in kg, c=specific heat capacity in J/kg°C, Δθ=temp change in °C)

Question 7

What is specific heat capacity?

Answer 7

The amount of energy required to raise the temperature of 1kg of a substance by 1°C

Question 8

What is specific latent heat?

Answer 8

The amount of energy needed to change the state (eg. solid, liquid, gas) of 1kg of the substance without changing its temperature

Question 9

What is meant by the specific latent heat of fusion?

Answer 9

The energy required to change 1kg of a SOLID to a LIQUID with no temperature change

Question 10

What is meant by the specific latent heat of vaporisation?

Answer 10

The energy required to change 1kg of a LIQUID to a VAPOUR with no temperature change

Question 11

What is the equation to calculate the energy change during a change of state?

Answer 11

E = m x L
(E=energy for a change of state in J, m=mass in kg, L=specific latent heat in J/kg)

Question 12

What is the efficiency equation?

Answer 12

efficiency=useful output energy/total input energy

Question 13

What are the 2 power equations?

Answer 13

P=E/t and P=W/t
(P=power in W (watts), E=energy in J, W=work done in J, t=time in seconds)

Question 14

What is power?

Answer 14

The rate of energy transferred or at which work is done

Question 15

Give 3 examples of renewable energy sources

Answer 15

Any from: biofuel, geothermal, wind, solar, hydroelectric, waves, tidal

Question 16

Give 3 examples of non-renewable energy sources

Answer 16

Any from: coal, oil, gas, nuclear(eg. uranium and plutonium)

Question 17

How can we reduce energy waste (2 examples)?

Answer 17

Lubrication
o Oil in a motor
o Reduces friction
o So less energy is lost (as heat) through friction

Thermal Insulation
o Double Glazing
o Less useful thermal energy lost

Question 18

What is the distance, speed and time formula?

Answer 18

speed = distance ÷ time

Question 19

What is the acceleration formula?

Answer 19

acceleration = change in velocity/time taken

Question 20

Which equation links acceleration, mass and resultant force?

Answer 20

F = m a
(F=resultant force, m=mass, a=acceleration)