Physics GCSE Equations

Question 1

what equation links work done, distance and force?

Yr 9 - P1: conservation and Dissipation of Energy

Answer 1

E = F x d

Question 2

GPE, mass, gravitational field strength and change in height

how do we calculate GPE?

Yr 9 - P1: conservation and Dissipation of Energy

Answer 2

GPE = m x g x change in h

Question 3

how do we calculate kinetic energy (KE)?

Yr 9 - P1: conservation and Dissipation of Energy

Answer 3

KE = 1/2 x m(v squared)

Question 4

how do we calculate efficiency?

Yr 9 - P1: conservation and Dissipation of Energy

energy can be given as a percentage

Answer 4

efficiency = useful energy output / total energy input

useful energy output = efficiency x total energy input

Question 5

which equation links energy transferred, time and power?

Yr 9 - P1: conservation and Dissipation of Energy

Answer 5

P = E / t

Question 6

what is Ohm’s law?
(state/describe Ohm’s law)

Yr 9 - P4: Electric Circuits

Answer 6

1. Ohm’s law states that at a constant temperature, the current across a resistor is directly proportional to the voltage across the resistor.
2. V = I x R
   voltage* = current x resistance

*voltage and potential difference are the same thing

an Ohmic conductor is something that obeys Ohm’s law.

Question 7

which equation links current, time and charge?

Yr 9 - P4: Electric Circuits

Answer 7

1. Q = I x t
2. charge (C) = current (A) x time (s)

Current is the rate of flow of charge.
(the amount of charge per second.)

Question 8

what equation links energy, voltage and charge?

Yr 9 - P4: Electric Circuits

Answer 8

1. V = E/Q
2. Voltage is the amount of energy carried per charge (or per electron)

Question 9

Ohm’s law: V = I x R

I-V graphs:
a) the steeper the gradient, the _____ the resistance (and the _______ the amount of current)
b) the shallower the gradient, the _______ the resistance (and the _____ the amount of current)

Yr 9 - P4: Electric Circuits

Answer 9

a) the steeper the gradient, the lower the resistance (and the greater the amount of current)

b) the shallower the gradient, the greater the resistance (and the lower the amount of current

Question 10

how do we calculate power?
(3 equations)

Answer 10

1. P = IV
2. P = I squared x R
3. P = E / t

2. power = current squared x resistance

Question 11

a = …

how do you calculate acceleration?

Answer 11

a = (v - u) / t

acceleration = (final velocity - initial velocity) / time

(m/s)2 = m/s / s

Question 12

how do you calculate weight?

(weight is a force, measured in Newtons)

Answer 12

weight = mass x gravitational field strength
w = m x g

N = kg x 10*

*assume gravitational field strength = 10 unless otherwise specified (i.e. 9.8)