### Activity Overview

In this activity, students investigate equilibrium of a point (a small metal ring) under the action of forces from 1, 2, 3 or 4 spring scales. They will find that the vector sum of the forces at a point must add to zero for it to remain in equilibrium.

### Learning Objectives

By the end of the activity, students should be able to:

- Read the force in a spring scale
- Trace the line of action of spring scale forces on a large sheet of paper
- Convert those lines of action into vectors and add them graphically (or algebraically, if given supplementary instruction)
- Demonstrate that a single, non-zero force cannot act at a point
- Show that if 2 forces act they must be equal and opposite
- Illustrate by example, that if 2 or more forces act at a point, their vector sum must be zero
- Demonstrate how the force in a single, angled spring scale can be experimentally resolved into its x and y components
- Give an example of a measurement that contains experimental error
And, if the Contract was used,

- Discuss how contracts can facilitate attainment of collective goals

Downloadables
### Tips for Using the Activity

Students should be encouraged to enjoy the Activity.

They should not be rushed or under pressure to obtain the “correct answer” or a high grade.

Instead, they should be encouraged to explore, and figure out how forces at a point must interact for equilibrium to exist.

### Equipment Design

The equipment was designed to be simple and intuitive to operate, informative to the students, and durable.

### Additional Information

See the **Downloadables** section for more information on this activity.