Using a force meter:

This is a lab intended to introduce quantitative dynamics. The key concept in dynamics is the force. The forces acting on an object determine its acceleration and thus its motion.

Force is measured quantitatively with a force-meter. A force meter is simply a spring with a calibrated ruler that gives the force acting on an object in Newtons.

Some forces, in addition to having a scale of Newtons, have another scale of grams. This, however, is very bad, and you should never use this scale! In my classes, I typically cover it up with duct tape. That is because grams are a measure of mass, not force. A force meter should be used only to measure force and never mass!

Picking the Correct Force Meter:

Every force meter has a particular maximum force. If you pull harder than the maximum force, then the force meter simply locks at the maximum (or "maxes out"), and it is impossible to get a reading. However, if you pull much weaker than the maximum force, then you will get in inaccurate reading. It is important to use the correct force meter for each task!

Rule 1:If your force meter maxes out before reading the correct force, use that force meter.

Rule 2: If you could use a weaker force meter and have it not max out, use the weaker force meter.

For each of the following list of tasks, use a force-meter to determine the magnitude of force necessary to complete the task. Some might require you to build a tiny contraption with duct tape to attach the force meter hook to something.
For each selection, pick the correct force meter, and explain why you selected that particular force meter.

1. Pulling your backpack across the table.
2. Lifting up your backpack.
3. Holding your backpack in the air.
4. Turning a doorknob.
5. Opening a cabinet door.
6. Pulling down the projector slide.
7. Any idea of your own.
8. One more idea of your own.