Wednesday, 5 February 2014
Would a penny dropped off The Empire State Building kill you if you were unlucky enough to stand in the wrong spot? I wanted a way to introduce drag along with vertical motion because ignoring air resistance denies the world students are already familiar with.
Fortunately, the Mythbusters tackled this myth in their first season and it’s on Netflix. So today, we did the following:
- Neglecting air resistance, how fast would a penny be moving just before striking the pavement after being dropped from the Empire State Building? Don’t tell the kids how tall the building is! Let them find it online. (~85 m/s or ~200mph)
- Would you survive a penny impact at that speed?
- Bring up Mythbusters (S1E4) — the Penny Drop myth is the first segment of the show and isn’t sprinkled throughout the episode, thankfully.
- Discuss terminal velocity and ask why a penny’s top speed is much lower than that predicted for the no-air-resistance case. Optional: pull up a drag equation and show what factors play into drag force.
We’ll be doing computational modeling of a case of drag, so this discussion was vital in my classes.