Q12. What was the net force acting on the cart during its rst bounce off the end of the track? (Hint: the sample rate given on the graph is important information!) Q13. If you look very closely at the graph between 3.6 to 7.4 seconds, you will see that it's not a straight line it has a kink in it. Wou will see the same kink from 7.6 to 10 seconds, as well.) Draw a free-body diagram for the cart going up & going back down the track & use them to explain the kink in this graph. GOING UP TRACK GOING DOWN TRACK