Wednesday, 17 February 2016
Set the kids up today in lab with the following question: given two forces of 0.6N each that are set up with a 90° angle between them, what force could you add to pull the system back into equilibrium? The kids have no experience with forces in two dimensions.
Most guessed 1.2N set up in the opposite direction of the angle bisector (“because the two original forces are equal”). So I sent them to the force tables to test. They were almost universally surprised to learn that 0.85N was the required balancing force.
Why? The best answers were some variation on “the original two 0.6N forces are pulling against each other somewhat.”
Lab setup: 5 force tables with 4 slotted mass sets each. Lab groups of 2-4 kids.
Here’s my lab: 2D Forces