Re: Physics Quiz 9
 

It can also be solved easily without conservation laws:

1) Vf = V - a*t (constant linear decel assuming const kinetic friction)

2) Vf/R = omega_f = alpha*t (constant rotary accel)

3) F*R = torque = I*alpha = (2*M*R^2/5)*alpha

4) alpha = (5*(F/M))/(2*R) = (5*a)/(2*R) (solve Eq3 for alpha)

5) Vf/R = (5*a)/(2*R)*t (subst alpha from Eq4 into Eq2)

6) Vf = (5/2)*a*t = (5/2)*(V-Vf) (cancel R and subst V-Vf for a*t from Eq1)

7) Vf = (5/7)*V (solve Eq6 for Vf)