Warm Up Activity
Carnival Trick
An old carnival trick involves placing a $100 bill between someone’s thumb and forefinger and telling the person that if he or she could catch it when it dropped, it would be his or hers. This trick depends on someone’s reaction time as well as the laws of motion.
For this activity you will need a meter stick and a partner. Rest your elbow on a table with your hand extended over the other side. Have your partner suspend the meter stick between your thumb and forefinger and note the centimeter mark on the meter stick that is between your fingers. Have your partner, without warning, release the meter stick and try to catch it. Note the centimeter mark on the meter stick where you catch it. The difference in values is the displacement that the meter stick fell.
Human reaction time is really fast, faster than a fraction of a second, so it’s nearly impossible to time it with a stopwatch, but by the end of this unit, you’ll be able to calculate your reaction time. You’ll also be able to figure out if you could ever win $100 in that old carnival game. You might even be able to decide if you could win the $100 in the carnival game if you were on the Moon.