Dollar Bill Response time

Challenge a friend to see if they can snatch a dollar bill between their fingers when you release it.

Time: one minute


  • dollar bill
  • a partner


  • Hold a flat, smooth dollar bill so it hangs straight down half-way between your friend’s finger and thumb.
  • Now, drop the bill and see if your friend can catch the falling bill.


  • Did your friend catch the bill?
  • Why do you think it is so hard to catch the bill?


If done right, your friend should never be able to catch the bill. According to the laws of physics, the bill will fall a distance of 8 centimeters in a time of 1/8 of a second but it takes longer for the signal to travel from the eye to the brain and back to the finger (1/7 of a second).


  • Now, try using a 12 inch ruler and measure who has the fastest reaction time. With the longer object, you should be able to snatch the ruler before it falls between your fingers… You can calculate who has the fastest reaction time.


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Coco Science

Coco is interested in STEAM with a particular interest in the A. She has a hamster named Marshmallow and likes to read, craft, cook and dance.