Physics year 11 start of new term cohort tests

Topic 1: Practical skills

1)      Independent variable = the thing you change in an investigation, dependant variable = the thing you measure in an investigation, control variables = anything you keep constant in an investigation.

2)      The resolution of a piece of equipment is the smallest value the equipment can read to e.g. a ruler can read to 1mm

3)      If you need to describe a straight line graph that goes through the origin you must say: The [write what is the on x-axis] is directly proportional to [write what is on the y-axis]. Examples in this paper:

4)      The uncertainty in a mean result gives you the range of values that you expect the true value to lie between. E.g. 120±5N means you expect the true value to be somewhere between 115-125N, but 120N is your mean result.

5)      To find uncertainty, you need to repeat your investigation. Uncertainty = ½ range of your repeated results. E.g. if test 1 = 5.2 seconds, test 2 = 5.6 seconds and test 3 = 5.5 seconds, your uncertainty is (5.6-5.2)/2 = 0.2s.

6)      You repeat results to look for anomalies and reduce the impact of random errors

7)      Dataloggers attached to probes are better than normal lab equipment because:

a.      The resolution is better

b.      It reduces the chance of human error

c.       You can take many results in quick succession

d.      You can take results over a long period of time e.g. over night

Topic 2: Forces and motion

8)      A scalar quantity has a magnitude (size) only, a vector quantity has a magnitude and direction.

All quantities can be split into scalars and vectors, these are just the most common examples AQA use but any can come up.

9)      Forces can be contact forces or non-contact forces.

e.      Contact forces: friction, normal contact force, air resistance and tension

f.        Non-contact forces: (there is a field) weight/gravitational force, magnetic force, electrostatic force between charged particles.

10)  Weight is the force acting on an object due to gravity. DO NOT CALL IT GRAVITY. It depends on the gravitational field strength and mass of the object and acts from the “centre of mass”.

11)  Newton’s first Law: An object will remain at rest, or in constant motion, unless acted upon by a resultant force (so if resultant force = 0, it will remain stationary or at a steady speed in the same direction, if resultant force is not 0, it will change speed and/or direction).

12)  The tendency of objects to continue in their state of rest or of uniform motion is called inertia.

13)  Newton’s Second Law: acceleration is directly proportional to resultant force and inversely proportional to mass

14)  Inertial mass is a measure of how difficult it is to change the velocity of an object, it is defined as the ratio of force over acceleration.

15)  Newton’s Third Law: If object A puts a force on object B, object B will put an equal and opposite force on object A.

16)  If you want to stretch, bend or squash an object, you need more than one force (one to hold it in place), otherwise the object will just accelerate; stretching an object stores elastic potential energy.

17)  The stretching force applied to an object is directly proportional to the extension (so is a straight line graph through (0,0)) up to the limit of proportionality.

18)  Elastic materials will return to their original shape after the deforming force is removed, inelastic materials will not (they are permanently deformed).

19)  Distance (scalar) is how far an object moves, displacement (vector) is how far an object moves overall from start to finish in a straight line with the direction.

20)  Speed (scalar) is how fast an object is going, velocity (vector) is the speed with direction.

21)  Typical speeds are:

g.       Walking - 1.5m/s

h.      Running – 3m/s

i.        Cycling – 6m/s

j.        Sound in air – 330m/s

22)  The gradient of a distance- time graph is the speed

23)  The gradient of a velocity-time graph is the acceleration, the area under the graph is the distance travelled.

Topic 3: Energy

24)  A system is a group of objects that interact.

25)  Energy can be stored or transferred:

26)  Conservation of energy means: The total energy of a system remains constant so energy cannot be created or destroyed; it can only be transferred between stores. 

27)  Efficiency is a measurement of how much useful energy comes out of a device, compared to how much energy went in

28)  Energy is measured in Joules (J).

29)  All energy transfers will have some wasted energy (nothing is 100% efficient), usually this is heat energy. Phrase this as ‘energy is transferred to the surroundings as heat, increasing the surroundings internal energy’.

30)  The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction across the material.

31)  Conduction is how solids transfer energy, as particles heat up they vibrate more, colliding with the particles next to them, passing the energy along. You can make buildings more efficient by using insulation because they reduce conduction. 

32)  You can reduce the wasted energy (by heat) from friction by using a lubricant such as oil.

33)  When discussing energy resources always say if they are renewable or non-renewable, if they release carbon dioxide so contribute to global warming or not, if they are reliable or not. 

34)  Renewable means the source of the energy will not run out: wind power, solar power, hydroelectric power, wave power, tidal power, geothermal power and biomass power. The non-renewable energy resources are coal, oil, gas and nuclear.

35)  Coal, oil and gas release carbon dioxide so contribute to global warming, they also release sulphur so cause acid rain. Biomass power is carbon neutral so they release carbon dioxide but this is balanced by the carbon dioxide the plants absorb when they are growing. 

36)  Reliable resources are: coal, oil, gas, nuclear, hydroelectric, tidal, biomass, geothermal. Unreliable resources are: solar, wind, wave. 

Topic 4: Electricity

37)  Current is the rate of flow of charge. It is measured by an ammeter and has the units Amps (A).

38)  Potential difference (p.d.) is the energy transferred per unit charge. It is measured by a voltmeter and has the unit Volts (V).

39)  Charge is measured in Coulombs (C).

40)  Resistance is a measurement of how difficult it is for current to flow and has the unit Ohms (Ω).

41)  Ammeters must be placed in series in the circuit, voltmeters must be placed in parallel around the component you want to measure the p.d. of.

42)  These circuit symbols:

43)  A series circuit is one where the current all flows through the same path. In a parallel circuit, there is more than one path that current can flow through.

44)  The current in a series circuit is the same the whole way around the circuit, the current in a parallel circuit splits up or joins together at junctions but the total current into a junction = the total current out of the junction.

45)  In a series circuit, the total potential difference of the power supply is shared between the components. In a parallel circuit, the potential difference across each branch of the circuit is the same as the power supply.

46)  In a series circuit, the total resistance = the sum of the individual resistors (resistance adds up), in a parallel circuit, the total resistance decreases and is less than any of the individual resistors.

47)  The total resistance when components are placed in parallel decreases because there are more paths for the current to flow through. Total current therefore increases, if current increases then resistance must have decreased.

48)  The resistance of a wire increases as its length increases, length is directly proportional to resistance.

49)  Mains electricity in the UK has a p.d. of 230V, a frequency of 50Hz and uses alternating current (AC)

50)  Direct current (DC), from batteries, is when the current flows in one direction only. Alternating current (AC), from the mains, is where the current is constantly changing direction.

51)  A UK plug has 3 wires

Topic 5: Particle Model of Matter

52)   The 3 states of matter can be described as:

53)   Density is the mass per unit volume.  Gases have the lowest density as they are spread out so there are less particles (and therefore less mass) in the same volume compared to liquids and solids.

54)   Internal energy = total kinetic energy + total potential energy of all the particles in the system (potential energy is to do with spacing: more spread out = more potential energy)

55)   When you heat up a solid, liquid or gas, it will have a rise in temperature, this means the kinetic energy of the particles will increase. Temperature is directly proportional to kinetic energy.

56)   Specific heat capacity is the amount of energy required to raise the temperature of 1kg of a substance by 1°C.

57)   When you melt or boil a substance (state change), the temperature stays constant so kinetic energy stays constant, however, the potential energy increases.

58)   Specific latent heat of fusion is the amount of energy required to change 1kg of a solid into a liquid at a constant temperature. Specific latent heat of vaporisation is the same thing but for a liquid into a gas.

59)   There is a pressure in a gas because the particles collide with the container walls and put a force on the wall. (pressure = force ÷ area).

60)   When you heat the gas, the particles move faster so hit the wall harder and more often, therefore pressure increases as the force increases.