Observing acceleration with a water accelerometer

By looking at a moving object you can easily see its position and have a sense of its velocity. Acceleration is harder. You will use a very simple accelerometer to see the effect of acceleration. A thin rectangular box is filled part way with water that may have added food coloring.

Part I: Calibrating the Accelerometer

1. Place the accelerometer on the table. Sketch the water in the accelerometer when it is at rest. What is the acceleration? Use the washable pen provided to mark the level of the water for this case.

2. Describe the water when the object moves at constant velocity. Does the direction of the velocity have any effect? Sketch the accelerometer and water level. What is the acceleration?

3. Describe the water when the object is accelerating to the right. (Push with your hand) Sketch the accelerometer. What is the direction of acceleration?

4. Describe the water when the object is accelerating to the left. Sketch the accelerometer. What is the direction of acceleration?

You can think of the water as an arrowhead pointing in the direction of acceleration.

Part II: Using the Accelerometer

1. A cart is rolled along a frictionless inclined table, moving uphill, momentarily stopping, and then moving downhill.
   1. When the cart is moving up the table, predict the direction of the acceleration (circle one)

           Up the table     Down the table      No acceleration     Other
         

   2. When the cart is at its maximum height, predict the direction of the acceleration (circle one)

           Up the table     Down the table      No acceleration     Other
         

   3. When the cart is moving down the table, predict the direction of the acceleration (circle one)

           Up the table     Down the table      No acceleration     Other
         

2. Get a cart. Incline your table (put books or something under the legs) so that one end is about 10-15 cm above the other. Clamp the accelerometer to the cart so that the water level in the accelerometer is horizontal when the cart sits still on the tilted table. Give the cart a small push up the table and draw the water level for each case in part 1. Note: Give a shove large enough that the cart goes almost the entire length of the table, but push smoothly, extending your arms from the elbow.
   

Does your experiment confirm your prediction, or not? Make a clear summary statement of the experiment.