FORMULAS

Question 1

Density

Answer 1

ρ = mv
- ρ = density, kg/m3
- m = mass, kg
- v = volume, m3

Question 2

Weight

Answer 2

W = mg
W = weight, N
m = mass, kg
g = acceleration due to gravity, m/s2

Question 3

Force

Answer 3

F = ma
F = Force, N
m = mass, kg
a = acceleration, m/s2

Question 4

Moment of a force about a point

Answer 4

τ=Fd
τ = moment of a force, Nm
F = Force, N
d = perpendicular distance from pivot to the
line of action of the force, m

Question 5

Moment of a force about a point pt.2

Answer 5

W=Fd
W = work done J (joules)
F = Force, N
d = displacement, m

Question 6

Kinetic Energy

Answer 6

K.E.= 0,5mv2
K.E. = kinetic energy, J
m = mass, kg
v = velocity. m/s

Question 7

Gravitational Potential Energy

Answer 7

P.E. = mgh
P.E.= potential energy, J
m = mass, kg
g = accerleration due to gravity, m/s 2
h = height, m

Question 8

Efficiency

Answer 8

E = useful energy converted/total input energy x100
E = output power/ input power x100

Question 9

Power

Answer 9

P = W/t = E/t = Q/t
P = Power, W
W = work done, J
t = time, s
E = energy transferred, J
Q = thermal energy transferred, J

Question 10

Pressure

Answer 10

P = AF
P = pressure, Pa or Nm-2
F = normal force, N
A = area, m2

Question 11

Liquid Pressure

Answer 11

P = hρg
P = pressure at depth h, Pa
ρ = density, kg/m3
g = acceleration due to gravity, m/s2

Question 12

Boyle’s Law

Answer 12

P1V1 = P2V2
P1 = pressure of gas at state 1
P2 = pressure of gas at state 2
V1 = volume of gas at state 1
V2 = volume of gas at state 2

Question 13

Specific Heat Capacity

Answer 13

Q = mcθ
Q = heat absorbed/released due to change of temperature, J
m = mass, kg
c = specific heat capacity, J/kgK
θ = change in temperature, K

Question 14

Specific Heat latent of vaporisation or fusion

Answer 14

Q = mL
Q = heat absorbed/released due to change of temperature, J
m = mass, kg
L = specific latent heat of fusion or vaporisation, J/Kg

Question 15

Object in Equilibrium

Answer 15

Σ clockwise moments =
Σ anti-clockwise moments about the same pivot

Σ upward forces = Σ downward forces

Question 16

Motions at constant acceleration pt.1

Answer 16

s = ut + 12 at2

v = average speed, m/s
v = final velocity, m/s
a = acceleration, m/s2

v2 = u2 + 2as

s = displacement, m
u = initial velocity, m/s
t = time, s

Question 17

Motions at constant acceleration pt.2

Answer 17

v = (v + u)/2
s = (v + u)t/2
v = u + at

v = average speed, m/s
v = final velocity, m/s
a = acceleration, m/s2

s = displacement, m
u = initial velocity, m/s
t = time, s

Question 18

Wave Equation

Answer 18

v = ƒλ
ƒ = T1
v = wave speed, m/s
ƒ = frequency, Hz
λ = wavelength, m
T = period, s

Question 19

Transformer equation

Answer 19

Np/Ns=Vp/Vs=Is/Ip

Np = number of turns in the primary coil
Ns = number of turns in the secondary coil
Vp = voltage across primary coil, V
Vs = voltage across secondary coil, V
Ip = current in primary coil, A
Is = current in secondary coil, A

Question 20

Refractive Index

Answer 20

n=sin i/sin r
n=c/v
sin ^c =1/n

n = refractive index
i = angle in air/vacuum
r = angle in medium
c = speed of light in vacuum, m/s
v = speed of light in medium, m/s
^c = critical angle

Question 21

Electricity pt.1

Answer 21

Q = It V = IR V = W/Q

Q = charge, C
V = potential difference across two points, V
R = resistance, Ω
P = power, W
I = current, A
W = work done between two points, J

Question 22

Electricity pt.2

Answer 22

ξ = total work done/Q P = VI
E = VIt = I2Rt = V2/Rt

Q = charge, C
V = potential difference across two points, V R = resistance, Ω
P = power, W
ξ = emf, V
t = time, s
I = current, A
W = work done between two points, J
E = electrical energy, J