phy p2 Flashcards
(184 cards)
A spring is elastically deformed.
What is meant by ‘elastically deformed’? (2)
(the spring) will return to its original shape/length
when the force is removed
Explain why a star (the same mass as the Sun) remains stable while it is in the main sequence stage of its life cycle? (2)
- the inwards gravitational force and the outwards force as a result of fusion
- are balanced / in equilibrium
Describe what will happen to a star (the same mass of the Sun) between the main sequence stage and the end of the star’s life cycle.
Include the names of the stages in the life cycle of the star. (3)
- (the star) will expand to become a red giant
- (then it will) collapse to become a white dwarf
- (then it will) cool to become a black dwarf
Give three uses of ultraviolet light.
energy efficient lamps
tan
sterilise surgical equipment
kill microbes
attract insects
detecting forged banknotes
water purification
How could you determine the speed of water waves in a ripple tank without measuring the wavelength of the wave? (3)
- use a metre ruler to measure the distance travelled by the wave
- use a stopwatch to measure the time taken for the wave to travel that distance
- find speed by dividing the distance travelled by the time taken
Explain how a moving-coil loudspeaker produces a sound wave. (4)
- the current creates a magnetic field
- which interacts with the permanent magnetic field
- this causes a resultant force causing the cone to move
- when the direction of the current reverses the force on the cone reverses (causing sound waves)
State two factors that would affect the size of the centripetal force of a satellite. (2)
- radius of the orbit / height above the Earth
- speed of the satellite
- mass of the satellite
In 2012 a skydiver jumped from a helium balloon 39 000 metres above the Earth’s surface.
The skydiver reached a maximum speed of 377m/s.
Jumping 39 000 metres allowed the skydiver to reach a much higher speed than a skydiver jumping from 4000 metres.
Explain why. (3)
at higher altitudes, the air is less dense
so air resistance is lower
(so) it the skydiver can fall longer before reaching terminal velocity
A skydiver jumps out of a plane at 4000m.
Explain the changing motion of the skydiver in terms of forces acting on the skydiver. (4)
- when he jumps his weight downwards is greater than air resistance / resultant force downwards
- (resultant force causes) acceleration
- (which) causes air resistance to increase
resultant force decreases to 0 - (and) the skydiver falls at terminal velocity
It is illegal for train drivers to drink alcohol before driving a train.
Explain how drinking alcohol would affect the stopping distance of a train. (3)
- alcohol increases reaction times
- which will increase thinking distance so stopping distance will increase
- because stopping distance includes both braking distance and thinking distance
A red filter is placed in front of a spotlight.
The spotlight is directed at a blue object.
Explain why the object appears black. (3)
- only red is transmitted by the filter
- blue object absorbs red light
- no light is reflected by the (blue) object
What is meant by a zero error?
when (measuring device) displays a reading when not connected / should be zero
Describe how an investigation could be improved to reduce the effect of random error. (2)
repeat (the investigation)
ignore anomalies and calculate a mean
Some stars are much more massive than the Sun.
Describe the life cycle of stars much more massive than the Sun, including the formation of new elements. (6)
Level 3: Scientifically relevant facts, events or processes are identified and given in detail to form an accurate account.
Level 2: Scientifically relevant facts, events or processes are identified and their relevance is clear. The account is not fully accurate.
Level 1: Facts, events or processes are identified and simply stated but their relevance is not clear.
Indicative content:
- fusion produces new elements
- cloud of gas / hydrogen and dust or nebula
- pulled together by gravity
- causing increasing temperature (to start the fusion process)
- (to become a) protostar
- hydrogen nuclei fuse to form helium nuclei
- and the star becomes main sequence
- hydrogen begins to run out
- helium nuclei fuse to make heavier elements
- up to iron
- the star expands (to become a)
- red supergiant
- (the star collapses rapidly) and explodes
- in a supernova
- creating elements heavier than iron
- and distributing them throughout the universe
- leaving behind a neutron star
- or a black hole
A ray of light from a ray box should be as narrow as possible.
Explain why using a wider ray would give less accurate results than using a narrower ray. (2)
it is harder to judge where the centre of a wider ray is
causing a larger uncertainty / increasing random errors
Ice hockey players wear protective pads filled with foam.
Explain how the protective pads help to reduce injury when the players collide. (3)
- the foam increases the contact time taken during a collision
- which decreases the rate of change of momentum
- which decreases the force
A portable power supply has an alternator connected to a transformer.
The transformer can be adjusted to have different numbers of turns on the secondary coil.
Suggest why. (2)
to vary the (output) potential difference
so that you don’t need a different alternator / generator for each / every (type of) device
Suggest the purpose of slip rings in an alternator.
to provide continuous contact (between the coil and brushes)
A remote control transmits radio waves to a car’s aerial.
The car aerial is connected to an electrical circuit.
Describe what happens in the electrical circuit when the car aerial absorbs the radio waves. (2)
(alternating) current is induced (in the circuit)
with the same frequency as the radio waves
Explain why a car has a maximum speed. (4)
- there is a maximum forward / driving force (provided by the motor)
- as the speed of the car increases air resistance increases
- until the resultant force is zero / until the forces are balanced / in equilibrium / until the size of the air resistance force is equal to the size of the forward force
- so the car can no longer accelerate / has reached terminal velocity
Describe a method a student could use to obtain results showing direct proportionality between force and extension.
Include a risk assessment for two hazards. (6)
Force and Extension RP6
Level 3: The method would lead to the production of a valid outcome. The key steps are identified and logically sequenced.
Level 2: The method would not necessarily lead to a valid outcome. Most steps are identified, but the method is not fully logically sequenced.
Level 1: The method would not lead to a valid outcome. Some relevant steps are identified, but links are not made clear.
Indicative content
- set up a clamp stand with a clamp
- hang the spring from the clamp
- use a second clamp and boss to fix a (half) metre rule alongside the spring
- record the ruler reading that is level with the bottom of the spring
- hang a 1 N / a known weight from the bottom of the spring
- record the new position of the bottom of the spring
- calculate the extension of the spring
- measure the extension of the spring
- add further weights to the spring so the force increases 1 N at a time up to 5 N
- for each new force record the position of the bottom of the spring and calculate / measure the extension
Risk Assessment
Hazard: clamp (stand, boss and masses) might fall off desk
Risk: injury to feet
Precaution: use clamp to fix apparatus to the bench or ensure that the slotted masses hang over the base/foot of the stand or ensure that the boss is screwed tightly into the stand and clamp or put (heavy) masses on the base/foot of the stand
or stand up so that you can move out of the way
Hazard: spring could break / come loose
Risk: damage eye
Precaution: wear safety goggles
if a risk assessment / hazard is not given, the answer can still reach level 3, but not full marks
How would a graph show direct proportionality? (2)
- straight line
- through the origin
What is the advantage of repeating meaasurements and calculating a mean?
reduces effect of random error
