Equations

Question 1

Forces and Motion

Answer 1

s = d/t

a = (v-u)/t

v^2 = u^2 + 2as

F = ma

W = mg

p = mv

F = (mv-mu)/t

moment = force × perpendicular distance from pivot

Question 2

Electricity

Answer 2

P = IV

E = IVt

V = IR

Q = It

E = QV

Question 3

Waves

Answer 3

v = fλ

f = 1/T

n = sin i/sin r

sin c = 1/n

NB:
- refractive index (n) does not have units because it is a ratio
- c = critical angle

Question 4

Energy resources and energy transfers

Answer 4

efficiency = (useful energy output/total energy output) × 100%

W = Fd

GPE = mgh

KE = 1/2mv^2

P = W/t or P = E/t

Question 5

Solids, liquids and gases

Answer 5

ρ = m/V

P = F/A

P = hρg
here, ‘P’ is pressure difference

p1/T1 = p2/T2

p1V1 = p2V2

𝜟Q = mc𝜟T

Question 6

Astrophysics

Answer 6

v = (2πr/T)

change in wavelength/reference wavelength = velocity of galaxy/speed of light

Question 7

Magnetism and Electromagnetism

Answer 7

Vp/Vs = np/ns

VpIp = VsIs
for 100% efficiency

F = BIL