# Exploration

 Explore the Mass and Spring simulation below for several minutes: Try clicking around Try dragging objects Try sliding sliders Try making the masses oscillate without stopping Try stopping the masses so they are in equilibrium file=MassSpringLab2.swf

Now that you have spent several minutes familiarizing yourself with the Mass and Spring simulation, complete the following multi-choice question. Feel free to use the simulation to help you answer the question.

# Free Body Diagrams

 One of the masses is hooked onto a spring. The mass and spring soon come to rest. Which free body diagram best represents the forces on the hanging mass when it is at rest? In the free body diagram the object is represented by the square, the force due to the spring is denoted by Fs, and the weight of the object is denoted by W. It may also help to think about the sum of the forces when an object is in equilibrium.

 Incorrect, the forces are not the same magnitude. Incorrect, the forces are not the same magnitude.

# Reflection

 Forces in equilibrium is a concept that will be very useful when completing the remainder of the activity. The best answer to the question above is (a) because the magnitude of the object's weight (W) is equal to the magnitude of the (upward) force from the spring (Fs).