solved physics problems

photo credit: The Hills Are Alive

Every morning a man walks his dog to the end of his very long driveway which is 300 meters.  While the man walks a straight line to the end of the drive, the dog runs all over the place!  Yet, every morning, the dog and the man reach then end of the road at the same time.  If the man’s average velocity is 2.8 m/s and the dog’s is 4.9 m/s, what is the total distance run by the dog?

average velocity, solved physics problem

The trick to solving this physics problem:

The key to solving this physics problem is to figure out based on the words in the problem that the time it takes to the man to reach the end of the road is the same time it takes the dog and to use that information mathematically to solve the problem.  This is another one of those physics problems where students feel like they don’t have enough information to solve the problem.  In this case, it’s not that the information isn’t there – because it is clearly stated in the problem – it is that it isn’t giving in “numbers”!

When you are reading physics problems and pulling out the “inputs” for your problem, be sure to also look for the “inputs” that are written in words instead of with numbers.