Physics past paper questions

Cloth becomes positively charged due to…

The movement of electrons from the cloth to the rod.

Describe the arrangement and motion of water particles in liquid water.

1. Water particles slide over each other 2. Water particles are closely packed 3. Water particles are irregularly arranged

Purpose of the brushes and the commutator in the DC motor.

1. Ensures a current is passed through the coil 2. Reverses the current in the coil 3. Every half turn

Kinetic energy store of the car must decrease when the MGU charges the battery pack because…

1. Energy can’t be created or destroyed 2. So the energy is transferred from kinetic store of car 3. To chemical store of battery pack

Positive aspects of generating electricity using solar farms:

Renewable, No greenhouse gases

Negative aspects of generating electricity using solar farms:

Sun doesn’t shine all the time, Output depends on location

Two disadvantages of using wind turbines to generate electricity:

Only generates electricity when wind blows, Noise pollution

Burning fossil fuels is harmful to the environment because…

Releases CO2 Which causes global warming

How the HEP station and wind farm can be used together to maximize the effectiveness of generating electricity.

Wind farm can’t store energy, Wind powering the pump when demand is low, Upper lake acts as an energy store for wind farm output

Pad becomes charged when rubbing the plastic parts, but not when rubbing the metal parts because…

Metal is a conductor, So (in metals) the electrons flow through the metal parts to earth, Electrons in a plastic are static and stay with the plastic

How an airbag reduces the force experienced by the dummy in the collision.

Increases the collision time, Reduces the rate of change in momentum

Give a reason for the difference between the found value for the specific heat and the true value.

ENERGY lost to surroundings

How a main sequence star evolves into a supernova.

Fusion of hydrogen in core stops, Core collapse, Restarts fusion in core, Becomes red supergiant, Fusion of heavier elements stop, Causes a massive explosion which is a supernova

How the discovery of red-shifted light supports the Big Bang theory.

Nearby galaxies show smaller red-shift/change in wavelength, Nearby galaxies are travelling slower than further galaxies, All light red-shifted suggests that universe is expanding, Suggesting that the universe was once a single point

Purpose of the brushes and commutator in the DC motor

Provides a current to the coil, Reverses the current in the coil, Every half turn

Energy store of the car must decrease when the MGU charges the battery pack because…

Energy transfer from kinetic, To chemical, As energy can’t be made or destroyed

Two conditions needed to overcome the effects of repulsive electrostatic force and achieve nuclear fusion:

High temp, Nuclei have higher speed and kinetic energy, High pressure, Nuclei more likely to collide

How force X and force Y change as the bag is moved towards the person’s foot:

Force X decrease, Force Y increase, Total force remains the same

How to determine the specific heat capacity of water.

Mass of water = (mass of water + cup) - mass of cup, Mass found on pan balance, Time taken using stopwatch, Temp change = final - initial OR can be set temp, Energy supplied = voltmeter reading x ammeter reading x time, Whole experiment repeated and averaged

Two reasons why the energy from the heater is not all retained in the thermal store of water:

Heat going to surroundings, Insulation not perfect

How a transformer works:

It steps up or steps down voltage, Current in primary coil produces magnetic field, Current is alternating, Causing a changing magnetic field in the core, The core strengthens the magnetic field, Field lines interact with secondary coil, Which induces a voltage in the secondary coil

Whether or not the energy in the kinetic store of the particles changes when the sample is changing state:

KE = constant, temp = constant, Speed of particles = doesn’t change

The principle of conservation of momentum:

Momentum before = momentum after an event

How the amount of current in the transmission cables increases the efficiency of transmission of electricity:

Current causes wire to heat up, Lower current, Means less energy loss to the surroundings

How the force applied on ball A compares with the force applied on ball B during the collision:

Both forces = same magnitude, Forces are in opposite directions

Discuss the advantages and disadvantages of generating electricity using solar power and geothermal resources

1. no greenhouse gases

2. weather-dependant

3. reliable resource

4. only installed in some areas

Suggest how increasing the strength of the magnetic filend will affect the proton when it is moving in the magnetic field. (2)

1. force increases

2. acceleration increases

Explain which side of the diagram contains stars with the highest surface temperature. (2)

1. left side

2. blue/white stars are the hottest

State which colour on the visible specturm has the shortest wavelength

violet

Explain how the current in the battery will change now that the resistors are connected in series. (3)

1. current decreases

2. resistance has increased

3. voltage stayed the same

4. any references to V=IR

Describe an investigation the student could use to find the specific heat capacity of water. (5)

• heater with power output of 50W

• power supply

• beaker

• water

• thermometer

• stopwatch

• connecting leads

• balance

1. measure final - inital temp of water

2. measure time taken

3. allow temp to increase to max after turning heater off

4. calculate total energy through E = Pt

5. measure mass of water

6. by finding difference between empty beaker and beaker+water

7. use of E = mcΔT

8. plot a temp-time graph

9. use gradient

The radiators transfer energy from the water to the air in the house.

The temperature of the water in the heating system decreases by 4°C due to

heat transferred to the air.

This causes the air in the house to increase in temperature by 15°C.

The mass of air in the house and the mass of water in the heating system are

approximately the same.

Explain why there is a larger temperature change in the air. (3)

1. energy lost by water = energy gained by air approxiamately

2. some thermal energy lost by surroundings

3. air and water have diff specific heat capacity

Explain why the mean force from the block on car 1 is smaller than the mean force on car 2. (2)

car 1 has a crumple zone which collapses a part of the car before colliding

car 2 doesn’t

1. crumple zone increases time taken for car to collide

2. so a smaller acceleration

Explain how CMBR supports the Big Bang Theory. (2)

1. CMBR appears to be the same in all directions

2. which implies that the Universe started from a single point

Describe the evolution of the Universe from the Big Bang until the present day. (3)

1. universe started as hot, dense point

2. universe has expanded since BB

3. universe has cooled since BB

Describe the evidence that supports the Big Bang Theory. (4)

1. CMBR

2. same in all directions

3. as it started as gamma rays and wavelength has increased as universe expanded

4. red shift of galaxies

5. further galaxes are moving away from each other

6. red-shift indicates that galaxies are moving away from each other

Compare the arrangement of particles in a solid with the arrangement of particles in a liquid. (3)

1. solid = regularly arranged

2. liquid = irregularly arranged

3. in both particles are closely packed

Explain what will happen to the magnitude of force F if the block is moved towards support B. (3)

1. force F increases

2. distance from support A increases

3. clockwise moment increases

4. anticlockwise moment increases to keep balance

Explain why the forces acting on the block are NOT an example of Newton’s third law of motion. (2)

1. forces are acting on the same body

2. forces aren’t the same type/origin

3. correct example e.g. weight is balanced out by gravitational force on block by Earth

Describe how the oscilloscope could be adjusted to show fewer wave cycles on the screen. (2)

1. adjust timebase by turning knob

2. to decrease timebase