general physics

Question 1

describe air resistance

Answer 1

Air resistance is a contact force. This is because it is due to the physical contact (collisions) between an object and the particles in the air.

Question 2

is weight scalar

Answer 2

no vector

Question 3

Why could the jumper reach a higher speed of he jumps from a higher altitude

Answer 3

The higher the altitude, the less dense air is so the diver experiences less air resistance so was able to accelerate for longer before air resistance equaled weight

Question 4

Why is the window designed to have the curved shape if inside pressure is more than outside pressure

Answer 4

The force from air pressure acting from inside to outside is bigger than force acting inwards , keeping window in position

Question 5

Why is a blue object appearing black under s red colour filter

Answer 5

The red colour filter only transmits red light, the blue objects absorbs the red light there is now light reflected off the blue objects and thus it appears black. Black objects absorb all wavelengths

Question 6

What is the advantage of repeating measurements and calculating a mean

Answer 6

Reduces effect of random errors

Question 7

How to work out speed of waves without the wavelength and the frequency

Answer 7

measure the distance travelled by a wave using a metre rule
And
measure the time taken (for the wave to travel the measured distance) with a timer
And
divide the distance by the time

Question 8

Why should a thin rag be used instead of a wider ray

Answer 8

it is harder to judge where the centre of a wider ray is
causing a larger uncertainty (in the measurements)
increasing random errors

Question 9

Describe a method the student could have used to obtain the results shown in the graph
above ( refraction and reflection)

Answer 9

• place a glass block on a piece of paper
• draw around the glass block
• use the ray box to shine a ray of light through the glass block
• mark the ray of light entering the glass block
• mark the ray of light emerging from the glass block
• join the points to show the path of the complete ray through the block
• and draw a normal line at 90 degrees to the surface
• use a protractor to measure the angle of incidence
• use a protractor to measure the angle of refraction
• use a ray box to shine a ray of light at a range of different angles (of incidence) • increase the angle of incidence in 10 degree intervals
• from an angle of incidence of 10 degrees to an angle of incidence of 70
degrees.

Question 10

When a light wave is refracted

Answer 10

Velocity changes

Question 11

The car aerial is connected to an electrical circuit in the car.
Describe what happens in the electrical circuit when the car aerial absorbs radio waves.

Answer 11

alternating) current induced (in the electrical circuit)
allow electrons vibrate / oscillate (in the electrical circuit)

Question 12

The car aerial is connected to an electrical circuit in the car.
Describe what happens in the electrical circuit when the car aerial absorbs radio waves.

Answer 12

alternating) current induced (in the electrical circuit)
allow electrons vibrate / oscillate (in the electrical circuit)

Question 13

Differences between radio waves and sound waves

Answer 13

• radio waves are transverse
• radio waves travel at a higher speed
• radio waves can travel through a vacuum

Question 14

Why does the car have a maximum speed

Answer 14

The car has a maximum force forward provided by the motor causing for the speed of the car to increase, air resistance also increases until it is eventually equal in size to the forward force so car does not accelerate

Question 15

Function of microphone

Answer 15

to convert (the pressure variations in) sound (waves) into variations in current / p.d

Question 16

How does a microphone work

Answer 16

sound (waves) cause the diaphragm to vibrate
the diaphragm causes the coil / wire to vibrate
the coil / wire moves through the magnetic field
the coil / wire cuts magnetic field lines
a potential difference is induce

Question 17

Control variable in Leslie cube practical

Answer 17

distance between each side (of the cube) and the (infrared) detector

Question 18

Control variable in Leslie cube practical

Answer 18

distance between each side (of the cube) and the (infrared) detector

Question 19

What is the Albedo value of a perfect black body?

Answer 19

Zero

Question 20

The average Albedo value of the Earth’s surface is 0.3
The Albedo value of thick cloud varies between 0.6 and 0.9
At night the air at point A cools faster than the air at point B.
Explain why

Answer 20

At night, more radiation is emitted from the Earth than absorbed from space
cloud REFLECT radiation (towards the Earth)
allow solar radiation for radiation
at A, (there is no cloud cover so) a larger proportion of radiation will be emitted into space

Question 21

How does a wave redact when it goes from deep to shallow water

Answer 21

velocity / speed is slower in shallow water
so edge of wave (front) entering shallow water slows down
but the part of the wave (front) in deeper water continues at a higher speed (leading to a change in direction of the wave fronts)

Question 22

Why dies a wave not refract if it enters

Answer 22

every point on the wave (front) enters / hits the shallow water at the same time
and so every point slows down at the same time

Question 23

What evidence could be used to strengthen conclusion for angle of incidence = angle of reflection

Answer 23

results could be collected for angles (of incidence) not yet measured

Question 24

What evidence could be used to strengthen conclusion for angle of incidence = angle of reflection

Answer 24

results could be collected for angles (of incidence) not yet measured

Question 25

Why is the induced current alternating

Answer 25

because the magnet changes direction

Question 26

The seismometer cannot detect small vibrations.
Suggest two changes to the design of the seismometer that would make it more sensitive to small vibrations

Answer 26

any two from:
• stronger magnetic field
allow stronger magnet allow heavier magnet bigger magnet is insufficient
• more turns on the coil
bigger coil is insufficient
do not accept more coils of wire
• turns pushed closer together
• spring with a lower spring constant
allow less stiff spring allow weaker spring
do not accept add an iron core

Question 27

Why are microwaves good for communication

Answer 27

can travel through the atmosphere

Question 28

When radio waves are absorbed by an aerial they may create an alternating current in an electrical circuit.
If an alternating current is created what frequency would there be

Answer 28

Same as radio wave

Question 29

Explain why the small hole looks black.

Answer 29

light (inside the tin can) is reflected many times before incident on the hole
at each reflection energy / light is absorbed so (very) little light / energy leaves the hole

Question 30

Explain why the small hole looks black.

Answer 30

light (inside the tin can) is reflected many times before incident on the hole
at each reflection energy / light is absorbed so (very) little light / energy leaves the hole

Question 31

Describe one piece of evidence that shows when a sound wave travels through the air it is the wave and not the air itself that travels. (separa

Answer 31

vibrating drum skin does not move the air away to create a vacuum (around the drum)

Question 32

Explain how the loudspeaker converts current in an electrical circuit to a sound wave

Answer 32

the current in the electrical circuit is varying
the current passes through the coil
the coil experiences a force (inwards or outwards)
reversing the current reverses the force
the size of the current affects the size of the force
the varying current causes the coil to vibrate
the (vibrating) coil causes the cone to vibrate
the vibrating cone causes the air molecules to move
the movement of the air molecules produces the pressure variations in the air needed for a sound wave
the air molecules bunch together forming compressions and spread apart forming rarefactions