Force and Motion

Paths with a rope

Procedure

Clear a corner of the classroom (or go on the playground). One student, the fixed pivot, holds the end of the rope while standing in the corner where walls A and B meet. One student holds the rope at the 5’ point and a second holds the rope at the 10” point. Keeping the rope straight and taut, challenge the two students at the 5’ and 10’ points to walk in a straight line away from wall A and toward the opposite wall

*Could they walk in a straight line to the other side of the room? *
*What shape of path did each student follow? *
Who had the longest path? How do you know?
Let two more students hold the rope at the 5’ and the 10’ marks. This time let the class suggest how to measure how far each one goes. Again, be sure the rope is taught and straight.

Who had the longest path? How do you know?
How far did the student at 5’ go? How far did the student at 10’ go?
Why do you think the student at 5’ had a shorter distance than the one at 10’?
All students should have the experience of being prevented from going in a straight line. This provides a kinesthetic grounding for seeing how a link also moves in an arc around a pivot.

Students may suggest a fair test of the lengths of the paths at the 10’ marker and the 5’ marker requires that the same student count steps at each location. If so, this is a good experiment to do. You can collect data on the number of steps taken at the 5’ and 10’ markers by different students, and compare results.