# Cliffhanger movie physics

1. Feb 6, 2006

### jimmy p

I'm not sure if a similar question has been asked before but here goes.

I was watching Cliffhanger the other night, and right at the end, the John Lithgow character plummets to his doom on top of helicopter. This sparked a discussion with my housemate as to whether he could survive the fall if he jumped off the helicopter right at the point of impact with the ground, disregarded debris and the inevitable explosion. For some reason I have it in my head that he can survive, where my housemate (probably rightly so) believes that it doesn't matter, he will die.

Who is right and why? (if that really needs to be answered)

thanks

JP

2. Feb 7, 2006

### DavidK

This depends on the speed of the crash. Assuming the helicopter is heavy enough jumping at the last second will only decrease your velocity at impact by about 3 m/s (the vertical velocity you reach initialy when jumping).

3. Feb 7, 2006

### HallsofIvy

Remember that, just before hitting the ground, you have the downward speed of the helicopter. Jumping out of the helicopter when it is a few inches off the ground is not as falling just those few inches. As DavidK said, you could only decrease your rate of fall slightly by your upward jump.

4. Feb 7, 2006

### DaveC426913

It also begs the question - would he be likely to survive the fall if he stayed in the helicopter? We intuit that it will kill him, but I'm not so sure. Why do we presume that a freefall of equal height might not kill him?

Consider the relative benefits of being in a helicopter:

1] A helicopter, while we think of it as a massive piece of machinery - is extremely light for its size (it's carefully built that way). This would make it an object that actually falls a fair bit slower than a human. Even mangled, the rotors still provide significant air resistance. I'll bet if you dropped a human and a helicopter from the same height, the human would hit much sooner (faster acceleration, plus higher terminal velocity). Helicopters, whle admittedly not experts at it, are still much better gliders than human bodies.

2] The helicopter would absorb the vast quantity of damage when it hit.

If one could minimize the subseqent squashing or battering inside a metal can - I would bet that a human would actually stand a much better chance of suriviving the initial impact if he were inside a helicopter than if he were freefalling.

5. Feb 10, 2006

### jimmy p

I forgot that I asked this... thanks for the answers guys, looks like I lost the debate. I'm not gonna tell him though