Formulae Flashcards
Average Velocity?
Instantaneous velocity?
Average = Δs/t
Instant = gradient of displacement-time graph
Average acceleration?
Instantaneous acceleration?
Average = Δv/t
Instant = gradient of velocity-time graph
Average angular velocity?
Instantaneous angular velocity?
Units?
Average: ω=Δθ/t
Instant = gradient of angle-time graph
Unit = rad s⁻¹
Average angular acceleration?
Instantaneous angular acceleration?
Units?
Average: α=Δω/t
Instantaneous = gradient of tangent to curve of angle-time graph
Units = rad s⁻²
Weight?
Unit?
W=mg
Unit = N (kg m s⁻²)
Coefficient of friction?
Unit?
µ=F/N
No units since it is a ratio
Pressure?
Unit?
p=F/A
Unit = N m⁻²
Unbalanced force?
F=ma
Momentum?
Units?
p=mv
Units = N s
4 equations of linear motion?
v = u+at s = 1/2(u+v)t v² = u²+2as s = ut+1/2at²
4 equations of angular motion?
ω = ω₀+αt θ = 1/2(ω₀+ω)t ω² = ω₀+2αθ θ = ω₀t+1/2αt²
Moment?
Units?
M=Fd
Units = N m
Mechanical advantage?
Units?
MA = dₑ/dᵣ (effort arm/resistance arm)
No units since it is a ratio
Tangential linear velocity?
v=rω
Tangential linear acceleration?
at=rα
Radial linear acceleration?
ar = v²/t = rω²
Angular torque?
M=Iα
Moment of inertia?
Units?
I=mk²
Units = kg m²
General radius of gyration?
k=√(I/m)
Radius of gyration of a solid ring or spoked wheel?
Of a solid disc (e.g. a flywheel)?
k=r
k=1/2r²