http://weelookang.blogspot.com/2014/05/tracker-rachelong-student-video-tennis.html physics of tennis ball drop in water Kinematics Model y = if ( t<0.29,(-2.137E0)*t^2-1.976E-1*t+2.310E-1,if(t<0.735,9.542E-1*(t)^2-9.368E-1*(t)+0.17,if(t<0.902,-9.661E-1*t^2+1.592E0*t-6.479E-1,if(t<1.169,6.172E-1*t^2-1.284E0*t+6.580E-1,0)))) https://www.dropbox.com/s/e8uvoq7eq1hxtd6/Rachelongapplicationsmodel.trz author of video: rachelong author of model: lookang |

## Questions:

- why is the value of ay determined in part one or first part not equal to -9.81 m/s^2? is the frame-rate changed accidentally during compression process in iMovie software?
- can you explain the motion using the following kinematics model y = if ( t<0.29,(-2.137E0)*t^2-1.976E-1*t+2.310E-1,if(t<0.735,9.542E-1*(t)^2-9.368E-1*(t)+0.17,if(t<0.902,-9.661E-1*t^2+1.592E0*t-6.479E-1,if(t<1.169,6.172E-1*t^2-1.284E0*t+6.580E-1,0)))) ?