# SHM or Not??

## Description

A ball
on an air track is attached to a compressed spring as shown in the
animations (position is in meters and time is in seconds). Each of the 5 graphs
CORRECTLY shows a different property of the motion of the ball. **
**

## Question

Determine
whether the green ball undergoes simple harmonic motion and state which graph(s)
tell you this.

## Instructor Resources

###### Reference: See Giancoli-PA: 11-1, Giancoli-SE: 14-2.

###### Answer:
Animation 5. Most students will think that this motion is
simple harmonic motion when they see the sinusoidal position vs. time graph
(students often perceive that a sinusoidal x vs. t graph proves simple harmonic
motion instead of a linear restoring force having a sinusoidal x vs. t graph).
They are still relatively convinced of simple harmonic motion when they see a v
vs. t graph, which still looks sinusoidal. However, the force vs. x graph (here
the acceleration vs. position graph) is what tells us whether the force is a
linear restoring force and whether we have simple harmonic motion. Here we do
not have a linear restoring force with the amplitude of motion shown.

###### Script Author: Mario Belloni