Formulas (Unit 1)

Question 1

Moment of a Force

Answer 1

Moment = Force = Perpendicular distance from pivot
M = F × D

Question 2

Equations of motion

Answer 2

v = u + at
s = ½(u + v)t
s = ut + ½at²
v² = u² + 2as

Question 3

Average velocity

Answer 3

Average Velocity = Total displacement ÷ Total time taken

Question 4

Impulse

Answer 4

F × t
Ft = mv - mu

Question 5

Momentum

Answer 5

p = mv

Question 6

Acceleration

Answer 6

a = (v - u) ÷ t

Question 7

Force

Answer 7

F = ma

Question 8

Work done

Answer 8

Wd = f × d
Wd = ½mv² - ½mu²
Wd = QV

Question 9

Potential Energy

Answer 9

p.e. = mgh

Question 10

Kinetic Energy

Answer 10

k.e. = ½mv²

Question 11

Efficiency

Answer 11

Efficiency = useful output energy ÷ total input energy

Question 12

Power

Answer 12

P = wd ÷ t
P = energy transfered ÷ time taken
P = Fv
P = IV
P = I²R
P = V² ÷ R

Question 13

Charge

Answer 13

Q = It

Question 14

e.m.f.

Answer 14

E = W ÷ Q

Question 15

Voltage

Answer 15

V = IR

Question 16

Resistance
(Resistivity)

Answer 16

R = ρl ÷ A

Question 17

e.m.f. of a cell

Answer 17

E = V + v
E = V + Ir
E = IR + Ir
E = I(R + r)

Question 18

Potential Divider

Answer 18

I = Vᵢₙ ÷ (R₁ + R₂)
Vₒᵤₜ = I × R₁
Vₒᵤₜ = (R₁Vᵢₙ) ÷ (R₁ + R₂)