Year 9 Physics calculations



Year 11

P2

Additional Physics

Higher Tier

Formulae Booklet

P2 1 Motion

1. Distance-time graphs:

The slope of the graph = speed of the object.

d = distance (m)

s = speed (m/s)

t = time (s)

2. Velocity-time graphs:

An upwards slope on the graph = acceleration

A downwards slope on the graph = deceleration (will be a negative number)

v = final velocity (m/s)

u = initial velocity (m/s)

a = acceleration (m/s2)

t = time (s)

The area under the line = distance travelled (m)

You will need to section your graph into rectangles and/or triangles.

Remember!

❖ Area of a rectangle = height x base

❖ Area of a triangle = ½ height x base

P2 2 Speeding up & Slowing down

1. Resultant force

F = force (N)

m = mass (kg)

a = acceleration (m/s2)

2. Stopping distance

Stopping distance = thinking distance + braking distance

3. Weight

Weight (N) = mass (kg) x gravitational field strength (N/kg)

P2 3 Work, energy and momentum

1. Work done

Work done = energy transferred

W = work done (J)

F = force (N)

D = distance moved in the direction of the force (m)

(Note the similarity to the equation used to calculate gravitational potential energy in year 10!)

2. Kinetic energy

Kinetic energy (J) = ½ x mass (kg) x velocity2 (m/s)

TIP: If you don’t think you can rearrange the KE formula during the exam, learn the rearranged formulae instead:

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3. Momentum

momentum = mass x velocity

P = momentum (kgm/s))

M = mass (kg)

V = velocity (m/s)

total momentum before = total momentum after

4 Conservation of momentum in an explosion

Remember the momentum of an explosion before = 0

Therefore, total momentum after explosion = 0

So: (mass of A x velocity A) = - (mass of B x velocity of B)

5 Changing momentum

Newton’s 2nd Law:

Force = change in momentum

time taken

(mv = change in momentum (kgm/s)

F = force (N)

t = time (seconds)

P2 5 Current electricity

1 Resistance

Resistance = potential difference

current

R = resistance = (ohms, Ω)

V = potential difference (volts, V)

I = current (amperes, A)

2 Resistance in a series circuit

Add up the resistance of all the components in a series circuit.

3 Current

Is a rearrangement of the resistance equation:

current = potential difference

resistance

P2 6 Mains electricity

1 Alternating current

Frequency (hertz, Hz) = 1 .

Time period (s)

2 Power of an appliance

power = energy transformed

time

ET = energy transformed (joules, J)

P = power (watts, W)

T = time (secs)

3 Power supplied

power supplied = current x potential difference

P = power supplied (watts, W)

V = potential difference (volts, V)

I = current (amperes, A)

4 Charge flow

charge flow = current x time

Q = charge flow (coulomb, C)

I = current (amperes, A)

t = time (secs)

5 Energy & potential difference

Energy transformed = potential difference x charge flow

ET = energy transformed (joules, J)

V = potential difference (volts, V)

Q = charge flow (coulomb, C)

P2 7 Nuclear Physics

1 Radioactive decay

❖ α-emission = atomic number (Z) down 2, mass number (A) down 4

❖ β-emission = atomic number (Z) up 1, mass number (A) stays same

❖ γ-emission = atomic number (Z) and mass number (A) both stay same

Learn these formula triangles and equations and you can’t go wrong!

❖ Remember before you start the exam write all the formula triangles down in the front so that you can look back at them.

❖ If you are unsure of the equation you need, use the correct triangle and cover up the part you want to work out.

❖ This will give you the equation you need!

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