physics p6

Question 1

how can you measure reaction time?

Answer 1

catch a falling ruler:
- person holds ruler above your hand and drops it
- the length of the ruler below your hand when you catch it indicates your reaction time

Question 2

what is thinking distance?

Answer 2

distance travelled during the time the car travels before hitting brake

Question 3

what factors affect thinking distance?

Answer 3

drinking alcohol
using drugs
fatigue/ tiredness

Question 4

what is braking distance?

Answer 4

distance travelled while force of the brake is applied to the car

Question 5

what are the factors that affect the braking distance?

Answer 5

brakes, surface car is driving on, speed

Question 6

what is stopping distance?

Answer 6

total distance the car travels from seeing problem to stationary:

thinking distance + braking distance

Question 7

what is renewable energy?

Answer 7

they will not run out in millions of years

Question 8

what is non renewable energy?

Answer 8

they will run out in the next millions of years

Question 9

give renewable energy sources

Answer 9

biofuels

the sun
tides
wind
waves
hot rocks beneath ground
water high up

Question 10

give non renewable energy sources

Answer 10

nuclear fuels (e.g uranium)
fossil fuels (e.g coal, oil, gas)

Question 11

what were nuclear fuels formed in?

Answer 11

stars

Question 12

why has the use of energy sources changed overtime?

Answer 12

• population increase
• use of devices that use fuels like cars
• electricity generation

Question 13

how do fossil fuels link to climate change?

Answer 13

burning fossil fuels produces carbon dioxide which contributes to climate change

Question 14

what is the national grid?

Answer 14

the power stations, underground and overland wires, transformers that supply electricity

Question 15

what do transformers do?

Answer 15

change the voltage (p.d) to reduce the heating effect

Question 16

what do step up transformers do?

Answer 16

increase the p.d to nearly 400,000V

Question 17

what do step down transformers do?

Answer 17

decrease the p.d to 230V you need at home

Question 18

what is the order of national grid?

Answer 18

power station
step up transformer
grid network (275,000v)
step down transformer
grid network (132,000v)
transformer substations
offices/ homes

Question 19

how can you show how energy is transferred in the national grid?

Answer 19

sankey diagram:
useful energy is straight + wasted energy moves away

Question 20

what is the voltage of mains electricity?

Answer 20

230V

Question 21

why is the heating loss minimised in national grid?

Answer 21

voltage is increased causing current to decrease

less current means less energy is dissipated

Question 22

what is a direct current?

Answer 22

current flows in one direction
cells and batteries supply d.c

Question 23

what is alternating current?

Answer 23

constantly changes direction

• from mains as it is anything plugged into a socket

Question 24

what are the wires apart of the three pin plug?

Answer 24

live wire
neutral wire
earth wire

Question 25

what is the live wire and where is it?

Answer 25

Brown wire that carries alternating current (230v) on right side

Question 26

what is the neutral wire and where is it?

Answer 26

Blue wire that completes the circuit on the left side

Question 27

what is the earth wire and where is it?

Answer 27

green + yellow wire that is the safety wire that is connected to ‘earth’ (large pole) - in middle of plug

Question 28

what does the fuse do?

Answer 28

- breaks circuit if there is too much current flowing by melting easily - it protects the wiring

Question 29

what is double insulation?

Answer 29

appliances with outer metal cases to prevent people getting electric shock