Objects that move in a straight line with a constantspeed—not speeding up or slowing down—have zero acceleration. Wecall this kind of motion: Uniform Motion. We can identifyuniform motion when the object travels equal distance intervals inequal times.

We can identify non-uniform motion, oraccelerated motion, when the object travels equal distanceintervals in unequal times. Finally, we have two types ofnon-uniform motion: motion with constant acceleration and motionwith a non-constant (or changing) acceleration.

Activity 1

Today you will analyze the motion of a cart travelingalong an inclined track. You will begin by doing a thoughtexperiment, predicting the motion of your object. Discuss yourideas among your group…it is okay to disagree!

Sketch an acceleration-versus-timegraph for an object, starting with some initial speed, traveling ona flat track. Remember, this sketch is a prediction; whatdo you think it would look like? Then sketch a velocity-versus-timegraph for the same case.

1. Explain the shape of your accelerationgraph.

2. Explain the shape of your velocity graph

Sketch an acceleration-versus-time graph and avelocity-versus-time graph for an object, starting with someinitial speed, traveling down an inclinedtrack.

3. Explain the shape of your accelerationgraph.

4. Explain the shape of your velocity graph

Activity2

Now, using a track, cart meter stick andstopwatches, you will make some measurements to determine if a carttraveling down a ramp follows uniform or non-uniformmotion.

First, mark a start point and end pointon your track that is at least 1.5mlong.

5. How many time/distance data points,between start and end, will be necessary to determine whether thecart is traveling with uniform or non-uniform motion? Explain yourchoice. Note: you may want to look at Questions 8 & 9 to helpinform your choice.

6. Now, outline your measurement plan(procedure) to make this determination of uniform or non-uniformmotion. You procedure should include clear instructions, such thatanyone could reproduce you experimentexactly.

7. Create a data table and record yourdata in the space below.

8. Now you will need to use your data tocalculate velocities and accelerations. Recall that we havediscussed average velocity as vavg = Δx/Δt as well as vavg = (vi +vf)/2. We also discussed average acceleration as aavg = Δv/Δt.Using these equations, calculate the instantaneous velocity of yourcart at each distance/time data point and the average accelerationbetween each pair of distance/time data points. When you havecompleted your calculations, organize your results into a tablewith four columns: time, position, velocity, and averageacceleration.

9. Now you will graph your results.Plotting [1] a graph of position (y-axis) vs. time (x-axis); [2] agraph of velocity (y-axis) vs. time (x-axis); and [3] a graph ofacceleration (y-axis) vs. time (x-axis). Be sure to fully labelyour graphs. This may be done on a computer or on graph paper.Attach your graphs to the back of thispacket.

10. Based on your data and results,answer the lab questions: does a cart traveling down a rampfollow uniform or non-uniform motion? If it followsnon-uniform motion, is the acceleration constant ornon-constant? Support your answer with evidence from yourexperiment.

11. Are you confident in your answer toquestion 10? Explain why or why not.

12. Now, compare your answer (andresulting graphs) to the prediction sketches you made in Activity1. Do your predictions match your results? If not, which do youbelieve (prediction or results) andwhy?

13. Finally, take some time to evaluateyour procedure. Do you think it was an effective procedure? Werethere any problems with it? How would you change/improve upon theprocedure if you were to repeat thisexperiment?

trial 1	trial 2	trial 3 Â	trial 4 Â	trial 5 Â
2.7s	2.45s	2.9s	2.58s	2.82s