Topic 1 formulas Flashcards
speed, distance and time
v = s/t
v = speed m/s
s = distance m
t= time s
Km/h to m/s
km/h —–> m/s (divide by 3.6)
m/s ——-> km/h (multiply by 3.6)
acceleration formula
a = Δv/Δt
Δ means change in
velocity = m/s
time = s
velocity equation
v = d/t
V = velocity m/s
d = displacement m
t = time s
density
p = M/V
p = density
m = mass g
v = volume ml
Newtons 2nd law
F=ma
F = force N
M = mass Kg
A = acceleration m/s^2
Mass vs weight
Fg = mg
fg = force due to gravity N
m = mass kg
g = acceleration due to gravity (I usually use 9.8m/s^2)
Hooke’s law
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
Circular motion formula
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)
moment formula
Moment = Force x distance (from pivot)
Moment N/m
Force N
Distance M
M = F x d
Momentum
P = m x v
P = momentum Kgm/s
m = mass Kg
V = velocity m/s
impulse
Δp = FΔT
Δp = impulse kgm/s
f = force N
Δt = change in time
Kinetic energy
Ek = 1/2 m x v^2
Ek = kinetic energy J (J = joules)
M = mass Kg
V = velocity m/s
Gravitational potential
Ep = mgΔh
Ep = gravitational potential J
M= mass Kg
g = gravitational field strength (usually 9.8m/s^2)
Δh = change in height M
Work
W = FD
W = work J
F = force N
D = distance M
Power
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.
Energy efficiency
Efficiency (%) = (useful energy/ total energy) x 100
The same principle can be applied to power.
Pressure
P = F/A
p = pressure pa (pa = pascal)
F = force N
A = area M^2
Pressure in liquids
P = ρgΔh
P = pressure Pa
ρ = density kg/m^3
g = gravitational field strength 9.8
Δh = change in depth m
SI units
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
prefixes
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