For Olympic runners and swimmers, a fraction of a second is often the difference between winning a gold medal or a bronze. Indeed, it's the distance between winning any medal or returning home with nothing but hopes at another chance in four more years. And while its impact is most dramatic in running events, speed isn't only a matter of crossing the finish line first. In sports, reaction time, the interval between stimulation and reaction, often determines who wins and who loses. Even more importantly, in real-life situations, like when driving a car, it can mean the difference between life and death. Measure your reaction time with the following project.
What You Need:
What You Do:
- Have your partner sit or stand with their arm on the flat surface so their wrist extends beyond the edge.
- Hold the meter stick vertically above your partner's hand, with the "0" end of the stick just above their thumb and forefinger, but not touching them.
- Instruct your partner to catch it as quickly as possible as soon as they see it begin to fall.
- Without warning your partner, drop the meter stick.
- Record how far it fell before your partner caught it. Consult the reaction time table to determine reaction time. Repeat at least two more times.
- Switch places with your partner and repeat.
In this experiment, your reaction time is how long it takes your eyes to tell your brain that the meter stick is falling and how long it takes your brain to tell your fingers to catch it. We can use the distance the meter stick fell before you caught it to figure out your reaction time. The following formula is the basis: d = 1/2 gt2.
In this formula, "d" equals the distance the object fell, "g" equals gravitational acceleration (9.8 m/s2), and "t" is the time the object was falling. To simplify the process, we've provided a reaction time table with the calculations already done.
Try it again with a dollar bill, only start with the bill halfway between the catcher's thumb and pointer finger. If you're really brave, you can up the ante and allow whoever catches the dollar bill to keep it. Unless someone anticipates the dollar bill being dropped, the 6-inch bill should fall completely through the catcher's fingers before the typical human reaction time (about 1/4 second) allows them to catch it.
For further study:
- Talk about what sports depend on having a fast reaction time. How about real-life situations?
- Try the experiment on a variety of people of different ages. Whose reaction time is faster? Boys or girls? Adults or kids?
- Repeat the experiment, only this time, have the catcher whistling throughout. Did that make reaction time faster, slower, or the same?
- Can you improve your reaction time by repeating the experiment several times daily? Practice for a week then test yourself again to see.