P8

Question 1

What is the average walking speed?

Answer 1

~1.4 m/s (5 km/h)

Question 2

What is the speed of sound in air?

Answer 2

340 m/s

Question 3

What’s the average human reaction time?

Answer 3

~0.25 seconds (250 milliseconds)

Question 4

What’s the formula for acceleration?

Answer 4

a = F/m

Question 5

How do you convert from km/h to m/s?

Answer 5

Divide by 3.6 (or convert step-by-step: km → m, hours → seconds

Question 6

What are the two components of stopping distance?

Answer 6

• Thinking distance: distance travelled during reaction time

• Braking distance: distance while slowing to a stop

Question 7

What factors affect thinking distance?

Answer 7

• Speed

• Reaction time

• Distractions

• Tiredness

• Drugs/alcohol

Question 8

What factors affect braking distance?

Answer 8

• Speed

• Road conditions

• Tyre/brake condition

• Vehicle mass

Question 9

What happens to stopping distance at higher speeds?

Answer 9

: It increases significantly due to increased kinetic energy.

Question 10

What danger is caused by hard braking?

Answer 10

Large deceleration → large force → potential injury

Question 11

How does a seatbelt reduce injury risk?

Answer 11

It stretches, increasing stopping distance and reducing force.

Question 12

What do crumple zones do?

Answer 12

They absorb energy, increase stopping time, and reduce force.

Question 13

What is the function of airbags?

Answer 13

Increase time for the head to stop moving → reduce neck force.

Question 14

How do fossil fuels generate electricity?

Answer 14

Combustion → thermal energy → steam → turbines.

Question 15

How does nuclear fuel generate electricity?

Answer 15

Fission → thermal energy → steam → turbines.

Question 16

What is the source of biofuel energy?

Answer 16

Combustion of plant-based material.

Question 17

How does wind generate electricity?

Answer 17

Turbines rotate directly due to wind.

Question 18

How does hydroelectricity work?

Answer 18

Falling water (GPE) spins turbines.

Question 19

What is tidal energy?

Answer 19

Water movement from tides turns turbines in tidal barrages.

Question 20

How does solar energy work?

Answer 20

Photovoltaic cells directly convert sunlight to electricity.

Question 21

What energy trend began in the late 1800s?

Answer 21

Rise in coal use during the Industrial Revolution.

Question 22

What increased in the early 1900s?

Answer 22

Use of petrol and natural gas.

Question 23

When did nuclear energy become more common?

Answer 23

Since the late 1900s.

Question 24

When did renewable energy use begin to rise?

Answer 24

Recently, with wind and hydro being most used.

Question 25

How is electricity transferred in the UK?

Answer 25

Via the National Grid — high-voltage overhead lines.

Question 26

Why use step-up transformers?

Answer 26

Increase voltage, reduce current, which reduces heat loss.

Question 27

What is the formula related to power loss?

Answer 27

P = I^2 R

Question 28

What do step-down transformers do?

Answer 28

Reduce voltage for safe domestic use.

Question 29

What is the frequency and voltage of mains AC?

Answer 29

50 Hz and 230 V

Question 30

What is DC?

Answer 30

Direct current — constant voltage (from batteries)

Question 31

What does the live wire do?

Answer 31

Brown, carries current from mains to appliance.

Question 32

What does the neutral wire do?

Answer 32

Blue, completes the circuit.

Question 33

What does the earth wire do?

Answer 33

Green/yellow, connected to casing — safely grounds excess current.

Question 34

Why is the live wire dangerous even when off?

Answer 34

It can still carry current if circuit is live.

Question 35

What is red shift?

Answer 35

The increase in wavelength of light from galaxies moving away.

Question 36

What does red shift support?

Answer 36

Evidence that the universe is expanding.

Question 37

What is CMBR?

Answer 37

Cosmic Microwave Background Radiation — stretched early-universe radiation.

Question 38

What does CMBR support?

Answer 38

The Big Bang Theory.

Question 39

What causes stars to form?

Answer 39

Gravity pulls dust and gas together, increasing temperature and pressure.

Question 40

What process powers stars?

Answer 40

Nuclear fusion of hydrogen into helium.

Question 41

What happens when fusion stops?

Answer 41

The star collapses — size determines the outcome.

Question 42

What does a small/average star become?

Answer 42

White dwarf after a planetary nebula.

Question 43

What does a massive star become?

Answer 43

Supernova, then a neutron star or black hole.

Question 44

What affects the radiation emitted by solar bodies?

Answer 44

Their temperature — hotter bodies emit more and shorter wavelengths.

Question 45

What are the rocky planets?

Answer 45

Mercury, Venus, Earth, Mars.

Question 46

What are the gas giants?

Answer 46

Jupiter, Saturn, Uranus, Neptune.

Question 47

Why do larger planets have rings?

Answer 47

Strong gravitational pull traps debris in orbit.

Question 48

What are moons?

Answer 48

Natural satellites that orbit planets.

Question 49

What are artificial satellites?

Answer 49

Man-made devices in orbit.

Question 50

What is a polar orbit used for?

Answer 50

Weather and surveillance — covers the Earth quickly.

Question 51

What is geostationary orbit used for?

Answer 51

Communications — satellite appears fixed over the equator.

Question 52

Why do planets orbit in circles?

Answer 52

Due to gravitational force from the Sun.

Question 53

What happens if a planet moves closer to the Sun?

Answer 53

Orbital speed increases due to increased gravity.

Question 54

What controls Earth’s temperature?

Answer 54

Balance of EM radiation absorbed vs emitted.

Question 55

What causes global warming?

Answer 55

More greenhouse gases → more absorption → rising temperature.

Question 56

What are P-waves?

Answer 56

Longitudinal, fast, travel through solids and liquids.

Question 57

What are S-waves?

Answer 57

Transverse, slower, only travel through solids.

Question 58

What do seismic waves tell us about Earth’s core?

Answer 58

S-waves don’t travel through it → liquid outer core.

Question 59

How is the ocean floor mapped?

Answer 59

Using SONAR — sound waves reflect off the seabed.

Question 60

What do high-frequency waves detect?

Answer 60

Small features, e.g. fish shoals.

Question 61

What do low-frequency waves detect?

Answer 61

Deeper sediments — they travel farther due to less energy loss.

Question 62

What are typical speeds in everyday life?

Answer 62

Walking: 1.4 m/s • Running: 2.5 m/s • Cycling: 6 m/s • Sound in air: 340 m/s • Wind speed: 5–20 m/s

Question 63

What is a typical acceleration for a car?

Answer 63

Around 2–3 m/s² (can vary depending on the vehicle).

Question 64

How do you convert units using ratios?

Answer 64

Use proportional reasoning: • 1 km = 1000 m • 1 hour = 3600 s

Question 65

How can you measure human reaction time?

Answer 65

• Ruler drop test: distance fallen is used to calculate time • Light or sound response timers

Question 66

What estimates can you make for large accelerations?

Answer 66

• Emergency stop: up to -6 m/s² • Rollercoasters or sports cars: 10–15 m/s²

Question 67

What are the potential differences in live, neutral, and earth wires?

Answer 67

• Live: ~230 V • Neutral: 0 V • Earth: 0 V (safety)

Question 68

Why is a live wire dangerous even when the switch is off?

Answer 68

It can still be at 230 V and cause a shock if touched. Touching live and earth together can complete a circuit through you