Chronology | Current Month | Current Thread | Current Date |
[Year List] [Month List (current year)] | [Date Index] [Thread Index] | [Thread Prev] [Thread Next] | [Date Prev] [Date Next] |
Please help me get a concept across to my students. Here is the problem:
A person rides in the back of a pick-up truck moving forward at +20 mph
(relative to ground). The person throws a brick toward the back of the
truck at -5 mph (relative to the truck). What is the resultant velocity of
the brick relatvive to the ground?
I know that the brick will move forward at + 15 mph relative to the ground.
My students can't really believe this. Oh, they will accept it simply
because I told them that is what happens, but they do not really believe
that you can throw something backwards yet have it really be moving
foreward relative to the ground. I have no modeling software (i.e.
Interactive Physics) at the moment. And short of going to the parking lot
with a truck and a brick (maybe basketball -- safer) I am at a loss getting
them to believe this.