Most MythBusters episodes have some cool physics. But what can you do about it? You can do MythBusters homework. Here some problems for you to consider regarding the latest show.
Spot Check Grant's Work
The don't normally display their work on the show, but in this case they show Grant Imahara's calculations. I won't say what he is calculating, but I will mention the myth. The myth they are looking at is the idea that someone could build a parachute from supplies in a hotel room and escape from some incredible height (like 30 stories).
Here is a shot of that scene (captured with my phone).
I have several questions to go with this image.
- What is Grant trying to calculate?
- Did he make any errors?
- Create a screencast that goes over all parts of this work. Remember, the screencast has to be under 5 minutes.
Even though that is three questions, this is still just one homework question.
Acceleration of a Parachute
While we are still looking at the parachute drop, here are some more questions. First, you might want to watch the parachute drop after show video. It has lots of useful information and shot clips in there.
- In the first set of tests, Buster was dropped from about a height of 200 feet. Use video analysis to estimate the impact speed for one of the tests (all three first versions of parachutes were about the same).
- Estimate the terminal speed of one of these first parachutes. Yes, it will just be an estimate. You will have to look up the drag coefficient for a parachute (although it appears that Grant already did).
- Based on your answer above, how high would you have to drop Buster so that he reaches 95% of the terminal speed before hitting the ground?
- For the first round of parachutes, Buster impacted with the ground and had a maximum acceleration of around 160 g's. If his average acceleration was just 80 g's (just a guess), how much was he compressed during impact? You will need your estimate of impact speed from above. You can get this either by estimating the terminal speed or through video analysis.
- For the last parachute drop (with the really big one), determine the acceleration of Buster after the chute fully opened. Was he still slowing down when he hit the ground?
Oh, I should add that for the video analysis questions you might want to use Tracker Video Analysis - it's free.
Motorcycle on Water
Why didn't the motorcycle make it across the lake? My guess is that it was slowing down once it hit the water. Once it slowed past some critical speed value, it crashed. So, first question: was the motorcycle decreasing in speed as it moved on the water? Second: was the acceleration constant? (I am assuming it was accelerating).
If the motorcycle did have a fairly constant acceleration, one way to go farther across the lake would be to start with a greater speed. Estimate the starting ground speed of the motorcycle so that it would travel 500 feet across water without crashing.
__Final point: __This is the best homework that money can buy (and it's free). Why? Try googling the answer to this homework. Just try it. Anyway, who would want to google such fun questions? Actually, if you wait too long to do your homework, you will be able to find the answer via google because I will have posted solutions.
Have fun.
