Here's another idea for measuring MINIBOT rolling friction.
Release the bot from the top of the pole and time (with a stopwatch) how fast it takes to fall a distance X. Do this several times and average the results, throwing away any outliers.
Make sure the motor leads are open-circuit, not shorted.
Then use this formula to calculate the friction force:
Code:
f = w - 2*X*M/(t^2)
f is friction force in Newtons
w is MINIBOT weight in Newtons
M is the mass of the MINIBOT in kilograms
t is the average time in seconds
X is the distance it fell in meters
For beginning physics students:
Code:
The above formula comes directly from F=M*a, assuming constant applied force:
F = M*a
(w-f) = M*a
a = (w-f)/M
v = integral(a*dt) = a*t = (w-f)/M*t (assuming V = 0 at start)
x = integral(v*dt) = integral(a*t*dt) = (1/2)*a*t^2 (assuming x=0 at start)
x= (1/2)*[(w-f)/M]*t^2
solve for f to get the formula