Physical quantity

equivalents

mass 1 Kg 1000g

1g .001kg

distance 1mm 0.001m

1cm 0.01m

1m 1000mm

1000m

1km

These are the “tricky” ones

Pre-fix Multiplier

nano (n) 10-9 .000000001

micro (μ) 10-6 .000001

milli (m) 10-3 .001

kilo (k) 103 1000

mega (M) 106 1000000

giga (G) 109 1000000000

If your quantity (number) has a prefix then you multiply the number part by the value of the prefix to get units.

Example: 120kJ = 120 x 103 = 120,000 J Example: 350 mm = 350 x 10-3 = 0.35 m

If you have a number and you would like to use a prefix then you divide the number by the value of the prefix to get the Number with a Prefix

Example: 120,000J = 120,000 ÷ 103 = 120kJ Example: 0.35m = 0.35 ÷ 10-3 = 350mm

kg (kilogram) is the only SI unit that has a prefix - all the others don’t i.e. A (ampere)J (joule) m (metre)N (newton)s (second)V (volt)W (watt)Ω (ohm)

Divide you page down the middle and labelBefore and After (collision).Draw a diagram!

Write down your formulas

Substitute values: Remember to look for stationary objects - their velocity is zero and that part of the equation goes away!

Now let LHS (before) = RHS (after)Then solve for unknown value (i.e. what the question asked you to find)

Note : the unit of momentum is kgm/s or kgms-1

Note : the formula for momentum is given as p=mv in the Data Booklet

Use “u” for velocity before and use “v” for

velocity after collision

Constant Velocity … (Newton’s 1st Law) Constant Acceleration due to gravity

Draw diagram or sketch

List known and unknown quantities

Draw line down centre of page

On LHS write Horizontal

On RHS write Vertical

t

uva

tvs

Constant Velocity Constant Acceleration

Time (t) is common to both horizontal and vertical motion

Speed orVelocity

(ms-1)

time (s)

acceleration

constant speed

deceleration

deceleration

constant speed

Distance travelled = Area under graph

NOTE: v > u gives acceleration; v < u gives deceleration or negative acceleration

Again, remember that VS= V1 + V2

… you don’t need to use formula 2 twice!

Try to use formula 1 first.You need 3 of the 4 terms V1, V2, R1 or R2.(VS is not required)

Use this formula if you can’t use formula 1. Look for VS in the question.

Before you begin. Remember that VS= V1 + V2

Now write down what you know and don’t know !

The question will indicate whether the temperature (Thermistor) or light (LDR) is increasing or decreasing.Use this information to start your answer e.g “As the light level falls the resistance of the LDR increases …”

The LDR or Thermistor

may be placed here – you need

to think how this affects

step 2

LDR1

R2

Vs

V2

Explain the Science of the LDR (L.U.R.D.) orThermistor (T.U.R.D.)

This could be any output device, e.g. relay, bell, buzzer etc.

Explain How the Transistor works:-Switches ON at the threshold voltage

0.7 V for npn transistor1.0 – 2.0 volts for

MOSFET

Copy this from the Physics data booklet

Read the question carefully and select two of the three terms (ratios)

shown in the formula – you should end up with a simpler relationship

containing two terms (ratios).

Cross multiply to simplify then solve for the unknown term..

Transformers are not 100% efficient due to•Heat loss•Magnetising currents•Sound (vibrations)

Cooling Curve

Temperature(T)

time(t)

Gas

Liquid

SolidWhen material is cooling it gives off heat

energyWhen its temperature is increasing the

material is absorbing heat energy

LED numerical questions are usually worth three marks.

The question usually gives the operational or working voltage of the LED… and the operational or operating current of the LED.Then it asks you to calculate R

Vs

RThe current through R is the same as the operating current of the LED

Remember to include unit Ω

This is where you

get the extra mark

If the question asks you to find a “half life” or “how long a sample takes to decay” or “the initial or final level of Activity” then it’s a good bet that you need a …………..

Activity (units)

Time (units)

Fill in the initial Activity

Fill in the initial Activity

Initial time = 0

Initial time = 0

0

Divide previous

Activity by 2

Divide previous

Activity by 2

Divide previous

Activity by 2

Divide previous

Activity by 2

Until you reach your

Final Activity

Until you reach your

Final Activity

Add one ½ Life to previous time

Add one ½ Life to previous time

Add one ½ Life to previous time

Add one ½ Life to previous time

Until your reach your Final timeUntil your reach your Final time

To find the number of half lives – count the number of entries you have Made in the time row, but don’t count the first one (the zero value).

You will get the Units from the question

To find the Half Life divide the final time by the number of half lives

Initially Vc = Logic 0 (0V)

Not gates inverts Logic to Logic 1 (5v)This is applied to top of R1Capacitor charge up to Logic 1 (5v)

Not gates inverts Logic to Logic 0 (0v)This is applied to top of R1Capacitor discharges to Logic 0 (0v)

The process repeats

R1

Logic 0 = 0VLogic 1 = 5V

Timing/ Frequency determined by R1 and C

½ mark

½ mark

½ mark

½ mark