Topic 1 formulas

Question 1

speed, distance and time

Answer 1

v = s/t

v = speed m/s
s = distance m
t= time s

Question 2

Km/h to m/s

Answer 2

km/h —–> m/s (divide by 3.6)
m/s ——-> km/h (multiply by 3.6)

Question 3

acceleration formula

Answer 3

a = Δv/Δt

Δ means change in

velocity = m/s
time = s

Question 4

velocity equation

Answer 4

v = d/t
V = velocity m/s
d = displacement m
t = time s

Question 5

density

Answer 5

p = M/V

p = density
m = mass g
v = volume ml

Question 6

Newtons 2nd law

Answer 6

F=ma
F = force N
M = mass Kg
A = acceleration m/s^2

Question 7

Mass vs weight

Answer 7

Fg = mg
fg = force due to gravity N
m = mass kg
g = acceleration due to gravity (I usually use 9.8m/s^2)

Question 8

Hooke’s law

Answer 8

K = F/x

K = spring constant N/m
F = force N
x = extension M

The formula is sometimes given as F= -Kx. The negative shows the direction

Question 9

Circular motion formula

Answer 9

F = mv^2/r

F = force N
m = mass Kg
v = velocity m/s
r = radius m

Don’t need to remember this formula but do in case.

A bigger force is needed if:
Larger mass (but constant v and r)
smaller radius (but constant m and v)
Large speed (but constant m and r)

Question 10

moment formula

Answer 10

Moment = Force x distance (from pivot)

Moment N/m
Force N
Distance M

M = F x d

Question 11

Momentum

Answer 11

P = m x v

P = momentum Kgm/s
m = mass Kg
V = velocity m/s

Question 12

impulse

Answer 12

Δp = FΔT

Δp = impulse kgm/s
f = force N
Δt = change in time

Question 13

Kinetic energy

Answer 13

Ek = 1/2 m x v^2

Ek = kinetic energy J (J = joules)
M = mass Kg
V = velocity m/s

Question 14

Gravitational potential

Answer 14

Ep = mgΔh

Ep = gravitational potential J
M= mass Kg
g = gravitational field strength (usually 9.8m/s^2)
Δh = change in height M

Question 15

Work

Answer 15

W = FD

W = work J
F = force N
D = distance M

Question 16

Power

Answer 16

P= w/t or P= ΔE/t

P= power W ΔE = change in energy J
t = time S
w = work J

Power is measured in Watts this is the equivalent to Joules per second.

Question 17

Energy efficiency

Answer 17

Efficiency (%) = (useful energy/ total energy) x 100

The same principle can be applied to power.

Question 18

Pressure

Answer 18

P = F/A

p = pressure pa (pa = pascal)
F = force N
A = area M^2

Question 19

Pressure in liquids

Answer 19

P = ρgΔh

P = pressure Pa
ρ = density kg/m^3
g = gravitational field strength 9.8
Δh = change in depth m

Question 20

SI units

Answer 20

mass = kg
length = m
time = s
area = m^2
volume = m^3
force = N
weight = N
pressure = Pa
energy = J
work = J
power = W
frequency = Hz hertz
p.d., e.m.f. = V volt
current = A ampere
resistance = Ω ohm
charge = C coulomb
capacitance = farad F
temperature = Kelvin = k
degree celsius = °C

Question 21

prefixes

Answer 21

G (giga) = 10^9
M (mega) = 10^6
K (kilo) = 10^3
d = deci = 10^-1 or 1/10
c = centi = 10^-2
m = milli = 10^-3
µ = micro = 10^-6
n = nano = 10^-9
p = pico = 10^-12