energy (p1)

Question 1

describe elastic potential energy:

Answer 1

• when stretching the spring, we’re applying a force to change the length
• this is called ‘doing work’
• we’re putting energy in to stretch the spring. the spring is storing the energy. this is called elastic potential energy
• the spring’s extension and the force applied is directly proportional. however, applying too much force to the spring will make it reach its limit of proportionality, where it can’t stretch anymore

Question 2

define ‘work done’:

Answer 2

energy transferred when a force is used to move an object over a distance
- essentially, work is done when energy is transferred from one store to another

Question 3

describe gravitational potential energy:

Answer 3

• the energy stored in an object due to its position above the Earth’s surface
• this is from the force of gravity acting on the object

Question 4

define specific heat capacity:

Answer 4

the energy required to raise the temperature of 1kg of a substance by 1 degree celsius

Question 5

define power:

Answer 5

• power is the rate at which energy is transferred or at the rate at which work is done
• power is measured in watts. 1 watt is an energy transfer (or work done) of 1J per second

Question 6

what is the law of conservation of energy?

Answer 6

energy can be transferred usefully, stored or dissipated, but it cannot be created or destroyed

Question 7

name three ways to prevent a house from becoming thermally conductive:

Answer 7

• walls are made out of an external brick wall and an internal breezeblock. this is very thermally conductive, so the cavity in the middle is packed with insulation
• double glazed windows as opposed to single glazed windows
• loft insulation

Question 8

define efficiency:

Answer 8

a comparison of the power output to the energy input in a given system

Question 9

evaluate the use of fossil fuels:

Answer 9

advantages:
- reliable
- release a great deal of energy (e.g. good for aeroplanes)
- abundant and relatively cheap
- versatile (very useful for powering vehicles)

disadvantages:
- releases carbon dioxide (climate change)
- non-renewable
- can release other pollutants (e.g. diesel releases carbon particles and nitrogen oxides)

Question 10

describe nuclear power:

Answer 10

• non-renewable, runs on plutonium and uranium
• once running, doesn’t release co2; extremely reliable
• contains highly dangerous radioactive materials; decommission takes ages and is expensive

Question 11

evaluate renewable energy resources:

Answer 11

advantage:
- renewable (obviously)
- don’t release carbon dioxide

disadvantage:
- wind and solar aren’t reliable
- hydroelectric is reliable but destroys habitats when built

Question 12

describe bio-fuels:

Answer 12

• other renewable energy sources only generate electricity, and we cannot always use this for transport
• biofuels are produced from plant materials, and don’t add co2 to the climate (carbon neutral)
• however, to grow the crops to create bio-fuels, it will take up food growing space, which may increase the price of food even more

Question 13

what is a system?

Answer 13

a system is an object or a group of objects.
- e.g. in a pendulum, the objects in the system would be the mass, string, and the fixed point at the top. air particles could also be considered part of the system.