Equations

Question 1

Bernoulli’s

Answer 1

Pt = Po + Ps

Question 2

Equation relating density, pressure and temperature at ground and altitude

Answer 2

ρ/ρo = Ps/Po x To/Ts

Question 3

Mach number

Answer 3

M = Vt / A

Vt - true airspeed
A - speed of sound in fluid

Question 4

Speed of sound

Answer 4

A = √(γ x Ra x Ts)

γ = Cp/Cv = 1.4
Ra - look up tables
Ts - temperature at altitude

Question 5

Equation relating MTTF and λ (failure rate)

Answer 5

MTTF = 1/ λ

Question 6

Equation relating reliability and λ (failure rate)

Answer 6

R = e^(-λt)

where t is time

Question 7

Equation for no-load speed Ω0 of a motor

Answer 7

Ω0 = Vdc / K

Vdc = Voltage
K = back-emf constant

Question 8

Equation for stall Torque

Answer 8

T0 = kI = (Vdc/R)K

Question 9

Equation for motor required torque

Answer 9

Tm = Jm * alpha

alpha = rotation speed/time taken

Question 10

Equation used to find gear box ratio when Tl = 0

Answer 10

Jm = Jl/(n^2)

Question 11

Equation to find maximum load acceleration

Answer 11

almax = 1/2 * Tp/Jm * 1/n

Question 12

Equation to find minimum gear ratio, n

Answer 12

Tp = Tl / n

Question 13

For mechanical actuator, give equation to find the equivalent inertia of mass

Answer 13

Jl = (λ/2pi)^2 * m

Question 14

For an unloaded potentiometer equation for a, R, Rp, Vo, and Vs

Answer 14

a = x/xt (linear)
a = theta/theta(t) (rotary)

R = aRp
Vo = aVs

Question 15

Equation to find error for loaded potentiometer

Answer 15

Error = Vo(Rm=inf) - Vo(Rm) / Vo(Rm = inf)