Zip Line Scene

The Physics Behind The Zip Lining Scene: Home Alone 1

The scene... 
(https://youtu.be/mDUSjBiHYeY?t=97 for fast-forwarded version)

What exactly is going on... 

Towards the end of the film, Kevin makes his great escape from Harry, Marv, and the house to the tree house via. zip line. What allows for Kevin to do so, as well as what we can find out about this scene can be explained with a few physics concepts.

What we know... 

- From watching Kevin going down the zip line from start to finish, we can approximately time his velocities and total time it took him to travel (v1 = Ø, v2 = 3m/s, t = 14s)

- There are forces that act on Kevin

- Newton's first law is displayed when Kevin partially crashes through the back wall of the tree house

So what we can discover/analyze is...

1. The estimated distance Kevin traveled by using the kinematics equation:
△d = (v1+v2/2)t

      = (Ø+3/2)(14)
      = 1.5 (14)

∴△d  = 21m

2. 

The force of gravity, normal, friction, and applied forces are all acting on Kevin as he pushes himself off of the windowsill, down the zipline,

3. The reason why Kevin kept moving even after the zipline had come to an end is attributed to Newton's first law which states that if Fnet on an object is Ø, the object will maintain its motion and how it will either remain at rest, or continue moving uniformly (at a constant speed in a straight line). So initially, Kevin is moving uniformly with the zipline handle, so we know Fnet = 0. When the zipline handle finally stops its journey at the end of the zipline, Kevin basically still has Fnet = 0 (because only Kevin's hands are attached to the handle still, so the rest of his body moves separately from the handle). Kevin then seems to be shown flinging off of the zipline handle, crashing into the tree house wall, only because the handle on the zipline stopped so suddenly, but Kevin did not and continued to move uniformly (as predicted by Newton's 1st law).