Answer
$25.33 \ seconds$
Work Step by Step
We know that the overall mass of the system is:
$=73+940=1013 \ kg$
We know that the acceleration is equal to the force of gravity minus the force of friction over the overall mass. Thus, we find:
$a= \frac{(73)(9.81)-(.057)(940)(9.81)}{1013}=.159\ m/s^2$
We now can find the change in time, using the same equation that the book uses in example 5.4. Doing this, we find:
$t =\sqrt{\frac{2x}{a}}=\sqrt{\frac{2(51)}{.159}}=25.33 \ seconds$
