P8

Question 1

How do you calculate reaction time

Answer 1

Thinking distance / Speed

Question 2

State one precaution a person can use to get accurate results when dropping a ruler

Answer 2

Drop ruler from same height above hand.

Question 3

How to calculate stopping distance?

Answer 3

Thinking distance + Braking distance

Question 4

What are the factors that affect thinking distance?

Answer 4

Time - tiredness, drugs, alcohol

Speed - faster you go , further you’ll travel

Question 5

What are the factors that affect braking distance?

Answer 5

Speed
Mass
Condition of brakes
Road conditions

Question 6

when speed increases what happens to thinking and braking distance?

Answer 6

Thinking distance increases at same rate

Breaking distance and speed have a squared relationship.

Question 7

Voltage is increased between transmission through the National Grid . How much would this increase in voltage affect the Current.

Answer 7

It will reduce current

as power = voltage * current

Question 8

The National Grid transfers power from power stations to homes and factories. Describe one risk and one benefit of using high voltages to transmit electricity

Answer 8

Risk - potential electric shock/death

Benefit - reduces heat loss, more efficient.

Question 9

Explain why radio waves may be produced by transmission lines.

Answer 9

AC produces oscillations which is type of radio wave.

Question 10

Explain why it is more efficient to transfer energy at high voltages

Answer 10

Lower current, less energy wasted

Question 11

Write one risk of living near a nuclear power station and explain how this risk is reduced.

Answer 11

Leak of nuclear waste. Can be reduced by using safer storage and methods of disposal

Question 12

Describe the advantage of wind turbines compared to conventional coal power stations.

Answer 12

Supplies more sustainable energy compared to non renewable

No polluting waste is produced

Question 13

The future demand for fossil fuels is expected to increase. Give two reasons why scientists are worried about this increase in demand.

Answer 13

Theres not much left - finite resource

Causes damage to environment , e.g. increase in greenhouse gases

Question 14

Nuclear fission can be used as a power source to produce electricity. Give one advantage and disadvantage of using nuclear power to produce electricity.

Answer 14

Good - preserves fossil fuels

bad - produces a lot of nuclear waste

Question 15

How do we know the universe is expanding

Answer 15

Red shift - light is shifted towards the red end of the spectrum
Suggests that all the distant galaxies are moving away from us very quickly.
Therefore universe is expanding

Question 16

What does CMBR show

Answer 16

Cosmic Microwave Background Radiation

Scientists can detect low frequency microwave radiation coming from all direction and all parts of the universe.

Question 17

Describe the Big Bang model

Answer 17

Big Bang model states that all the matter in the universe occupied a single point. The single point exploded (The Big Bang) causing the universe to start expanding.

Question 18

State 2 pieces of evidence that support the Big Bang model

Answer 18

Red shift of light from distant galaxies

CMBR

Question 19

What is the life cycle of stars

Answer 19

Stars first form clouds of dust and gas
Due to gravity they spiral and form a protostar
Fusion occurs to form helium nuclei and a main sequence star is formed
Eventually hydrogen in the core begins to run out and fusion of heavier elements occur so red giant and red super giant form.

Red giant - when it runs out of fuel it becomes unstable and ejects a nebula which leaves behind a white dwarf. this cools down and eventually fades away.

Red super giant - when it runs out of fuel they collapse in on themselves in a massive explosion - SUPERNOVA.

the exploding supernova leaves a dense core called neutron star.
If star is big enough it could leave a black hole - super dense point where light can’t escape.