Questions Corrections 2020

Question 1

Describe the life cycle of stars much more massive than the sun including the formation of new elements

Answer 1

Fusion produces new elements
Nebula is pulled together by gravity causing an increasing temperature to become a pro star

Hydrogen nuclei fuse to form helium nuclei and the star becomes main sequence until the hydrogen begins to run out
The helium nuclei fuse to form heavier elements up to iron
Then the star expands to a red super giant and explodes (supernova)
Creating elements heavier than iron and distributing them throughout the universe
Leaving a neutron star or a black hole

Question 2

What property of a star does the range of wavelengths depend on

Answer 2

Temperature

Question 3

Explain why using a wider ray would give less accurate results than using a narrower ray

Answer 3

It is harder to judge where the centre. of the ray is
Causing a larger uncertainty

Question 4

What is meant by momentum is conserved

Answer 4

Total momentum before=total momentum after

Question 5

Explain how protective pads filled with foam help to reduce injury when the players collide

Answer 5

Increase the time taken to stop
So the rate of change of momentum decreases
Reducing the force

Question 6

Describe what happens in the electrical circuit when the car aerial absorbs radio waves

Answer 6

Current induced in the electrical circuit
With the same frequency as the radio wave

Question 7

Give two ways in which radio waves are different to sound waves

Answer 7

Radio waves are transverse
Radio waves are electromagnetic

Question 8

Explain why the car has a maximum speed

Answer 8

There is a maximum forward force provided by the motor
As the speed of the car increases air resistance increases
Until air resistance is equal in size to forward force
So the car can no longer accelerate

Question 9

Explain why an alternating current is induced in the coil

Answer 9

The coil cuts magnetic field lines
A potential difference is induced
So there is a complete circuit so a current is induced
Every half turn the potential difference reverses direction
So the current changes direction

Question 10

Suggest the purpose of the slip rings

Answer 10

Provides continuous contact between the coil and the transformer

Question 11

Explain why the handle of the alternator becomes much easier to turn when the alternator from the portable power supply is disconnected

Answer 11

There is no induced current
So no magnetic field
To oppose the movement of the coil