Work, Power and Electricity Generation

Question 1

What is energy transferred (J) equal to?

Answer 1

Work done (J)

They are essentially the same thing

Question 2

What is the relationship between work done, force and distance moved?

(Symbol and word equation)

Answer 2

• W = F x D
• Work done (Joules) = Force (Newtons) x Distance moved (Metres)

Remember work done = energy transferred

Question 3

What is the relationship between gravitational potential energy, mass, (change in) height and gravitational field strength?

(Symbol and word equation)

Answer 3

• GPE = M x G x H
• Gravitational potential energy (Joules) = Mass (Kilograms) x Gravitational Field Strength (n/kg) x Height (Metres)

• Therefore, if an object is lifted up it will gain GPE, and if it falls, it will lose GPE
• The gratiational field strength on earth is 10 (9.81) n/kg

Question 4

What is the relationship between kinetic energy, mass and speed?

(Word and symbol equation)

Answer 4

• KE = 1/2 x M X V²
• Kinetic Energy (Joules) = 1/2 x Mass (Kilograms) x Velocity (M/S)²

Question 5

How is gravitational potential energy linked to kinetic energy?

Answer 5

• GPE = (is all transferred to) KE assuming there are no wasted energy transfers
• This means that when an object is lifted and gains GPE, all of this energy will be transferred into KE as it falls and gains velocity

Question 6

What is power?

Answer 6

The rate of energy transfer

You can link it back to electricity, where energy transferred = current x voltage x time, so basically power = energy transferred/time as current x voltage = power

Question 7

What is the relationship between power, work done and time?

(Symbol and word equation)

Answer 7

• P = W/T
• Power (Watts) = Work done (Joules)/Time (Seconds)

So this is the same as power = energy transferred/time

Question 7

How is electricity generated using wind power?

Answer 7

• Kinetic energy from the wind spins a turbine
• The kinetic energy from the turbine transfers to electrical energy

Question 8

How is electricity generated using tidal/hydroelectric power?

Answer 8

• Kinetic energy from the movement of the waves/water falling from a height spins a turbine
• The kinetic energy from the turbine transfers to electrical energy

Question 9

How is electricity generated using geothermal power?

Answer 9

• Heat energy from hot rocks/magma heats water in order to produce steam
• The kinetic energy from the steam rising spins a turbine
• The kinetic energy from the turbine transfers to electrical energy

Question 9

How is electricity generated using solar heating systems (solar panels)?

Answer 9

• Infrared (thermal) radiation from the sun is used to heat water in order to produce steam
• The kinetic energy from the steam rising spins a turbine
• The kinetic energy from the turbine transfers to electrical energy

Alternatively, the solar heating systems can be used to heat water for household use

Question 9

How is electricity generated using solar cells?

Answer 9

Light energy from the sun is transferred directly into electrical energy

Question 10

How is electricity generated using fossil/bio fuels?

Answer 10

• Fossil/bio fuels such as methane are combusted in order to produce heat energy
• This heat energy heats water in order to produce steam
• The kinetic energy from the steam rising spins a turbine
• The kinetic energy from the turbine transfers to electrical energy