Week 13 CMT Style Problem - 4th Grade


Lightning Strikes

You will need a ruler to do this problem.


People are standing at the four points A, B, C and D. They saw lightning strike at point E. Because sound travels more slowly than light, they did not hear the thunder right away. You will need a ruler to do this problem.

One way to estimate how far away the lightning is from where you are is to count how many seconds the sound came after the lightning and then divide by 5. That will be how many miles the lightning is away from you. For example, if you hear thunder 20 seconds after the lightning then the lightning hit about 4 miles away.

  1. How far away are points A, B, C and D, in miles, from the lightning strike?

  2. Who heard the thunder first? Why?

  3. Who heard it last? Why?

  4. How long after the lightning did the person at Point B hear the thunder. (Hint multiply how many miles away they are times 5).



Now suppose lightning strikes again at a different place. The person at A and the person at C both hear the thunder after the same amount of time. Show on the map above 2 places where the lightning might have struck.