ShareForce & Motion - Watch Out! They're On a Collision Course!
Have you seen the movie "Freaky Friday?" In this movie a mother and daughter switch bodies. After the mother and daughter have switched bodies, they decide that they want to get back in their own bodies but they don't know how to get back to the way they originally were. In one scene the mother and daughter decide that if they run into each other hard enough that they might be able to switch bodies once again. They did manage to knock each other down and have a bit of a headache, but that was about it. They were still in the wrong bodies.
In everyday life we seem to be on a collision course with one thing or another. Instead of hurting ourselves we will just try a simple experiment.
Try It!
Materials:
- Two three-foot long wood dowels (one- to two-inches in diameter)
- Masking tape
- Rubber ball
- Steel ball bearing
- Cork ball
- Marble
- Wooden ball
- Each ball should be about the same size.
Procedure:
- Lay the dowels side by side and tape the ends together.
- This makes the track for racing the different balls.
- Create a chart like the one below to record your observations.
| Two Racing Balls | What do you think will happen when they collide? | What actually happened when the collision occurred? |
| Cork / Wood | ||
| Cork / Marble | ||
| Cork / Rubber | ||
| Cork / Steel | ||
| Marble / Wood | ||
| Marble / Rubber | ||
| Marble / Steel | ||
| Wood / Rubber | ||
| Wood / Steel | ||
| Steel / Rubber |
Safety:
Be careful to catch each ball so it does not hurt another person.
Some things can crash into one
another without even trying. Have you watched a football game? The receiver
(the one who catches the ball) runs in attempt to score a touchdown. On
his way to the end zone the receiver might be run into or crashed into
by an opposing team member. If the receiver is a lightweight (let's say
like a marshmallow) and the opposing team member is a heavy weight (let's
say like a rock) what will happen?
Let's compare the rock and marshmallow. Grab a handful of miniature
marshmallows and a handful of big rocks 
(quarter
sized if possible). Drop the marshmallows on the ground. Now throw the
rocks on top of the marshmallows as hard as you can. (Draw a plate-sized
circle on the ground. Keep all the rocks and marshmallows in this area).
What happened to the marshmallows? Did you find that some of the marshmallows
were smashed or dented, maybe even stuck to the rocks? Now let's reverse
the test. Put the rocks on the ground and drop the marshmallows on top
of the rocks. Were any of the rocks damaged? Why or why not?
Another experiment you may want
to try will require a soccer ball and a wall. Try rolling a ball
gently towards the wall. See how close you can roll the ball to
the wall without actually touching it. Have a friend try this with
you and see which one of you can get the closest. Now roll the ball
with more force to the wall in order for it to bounce off of the
wall and reach a target zone.
See which one of you can get closest to the target. Now mark off a point zone like you would see on a target. Your target zone can be easily made just by making lines on the floor using masking tape. Your goal is to get the most points. Use the chart below to explore the motion of the ball.
| How far do you think the ball will get to the wall without touching it? | How close did the ball actually get? |  |
How close to the tape line do you think you can roll your ball? | How close did you actually get? |
Please record your guesses and answers in inches.
