Toy Car Motion Lab



Name: _________________________________ Period: ____

Toy Car Motion Lab

Part I: Create a hypothesis, figure out the time between dots at constant velocity (see Part I sheet)

PURPOSE: To observe the motion of a toy car, create and analyze position versus time and velocity versus time graphs of this motion (extra credit acceleration-time).

HYPOTHESIS: You need to write what you think will happen in terms of the motion of the car, as well as what your position and time graph and velocity and time graph will look like when completed.

My hypothesis:

MATERIALS: Ticker tape Spark Timer

Meter stick Pull-Back Toy car

Long Flat Surface Masking tape

PROCEDURE:

****DO NOT USE TICKER TAPE WITH TIMER YET!!!****

TRIAL RUN WITH TIMER OFF:

1. Set up a horizontal runway. Make sure the car has enough space to stop. Check with teacher before doing any experiment!!!

2. Thread the ticker tape through the timer (curved downward). Make sure there are no tangles, etc that may prevent the car from running smoothly.

3. Attach the long length of ticker tape to the back of a toy car using the masking tape. Make sure it is long enough to record the entire speed!

4. DON’T TURN ON THE SPARK TIMER YET. Set up the ticker timer by plugging it in. Choose a starting Hz for your spark timer ( ______ Hz

Note the teacher’s instructions about the spark timing before you start.

5. Note the distance you want to pull the car back, then pull it back positioning the car close to the spark timer pointed straight down the “runway”.

6. Let go of your car with the timer OFF, and see how the tape runs through the timer. When the car has stopped, the end of the tape should end up either still in the timer or just out of the timer.

7. Adjust accordingly. Repeat with timer off as necessary.

EXPERIMENTAL TEST RUN:

8. Setup by Repeating steps 1, 2, and 3.

9. Make sure your car is at the correct pull back distance (control variable).

10. Check the starting Hz for your spark timer and record _______Hz

Note the teacher’s instructions about timing before you start.

11. Start the spark timer. When your team is ready, release the toy car.

12. When the toy car has stopped, stop the spark timer also.

13. Write your name and class period on the back of your ticker tape, and move forward on the lab using the ticker tape data. Keep these in the classroom – do not lose.

Part II Analyzing Data

DATA/RESULTS:

1. Use the data table with the following headings. Make sure to understand/read carefully what each column asks for data input… collaborate with your group. [pic]

2. If you’re at 60Hz, on your length of ticker tape, count and mark off every 6th dot.

3. The ticker timer makes 60 dots per second. Therefore, the time recorded in the data table should be tenths of a second (0.0s = dot #1, 0.1s = dot #6, 0.2s = dot #12, etc).

4. Figure out your UNITS of measurement and look at the diagram below:

Example:

|Time (t) |Position (x) |

|0.00 |0.00 (d0) |

|0.10 |2.54 (d1) |

|0.20 |6.73 (d2) |

|0.30 |10.28 (d3) |

|… |… |

5. Using a meter stick, (if you used 60Hz) measure the length from the first dot to the 6th dot. Record the length in the position column of your table.

6. Then measure the length from the first dot to the 12th dot. Record. Repeat the process for every 6th dot, always measuring from the first dot. This is recorded in the position column of your table.

The Total Distance Measured/Time (Dot Time Period from Part I) = Average Velocity

Part III Creating Graphs

7. Create a position-time graph from the data table. Label all axes.

8. From the position-time graph, create a velocity-time graph. Or simply fill in the rest of the data table (calculate change in position over change in time = velocity).

9. Make sure all graphs are clearly labeled, show appropriate scales on the axes, and have titles. Connect the points with an appropriate line of best fit (straight or curved). The line of best fit can be created using Excel -and it gives you a formula too!

• Use instantaneous velocities (see reading below for description). Make sure you show these tangents (use different colors help to make it clear)! Remember to show sample calculations for this.

---------------------------------------------------------------------------------------------------------READ THE FOLLOWING:

There is a special thing called instantaneous velocity. That's the velocity at a split second in time. Above, we were talking about your speed and direction over a long period of time. Why would you need to measure a velocity at one moment? Think about the moment you drove over the manhole. It's important to know if you were going 1 km/hr when you drove over the manhole, or 60 km/hr. It wouldn't help you to know that your average speed was 30 km/hr.

The term "instantaneous" refers to something physicists call a limit. Scientists "limit" the amount of time they do the measurement. When the "limit" moves to zero, that limit is one tiny moment in time. A physicist would measure your velocity as the "limit for a period of time", zero, to get the instantaneous velocity.

Changing Your Velocity (acceleration):

When velocity is changing, the word acceleration is used. Acceleration is also a vector. You speed up if the acceleration and velocity point in the same direction. You slow down (also referred to as decelerating) if the acceleration and velocity point in opposite directions. When you accelerate or decelerate, you change your velocity by a specific amount over a specific amount of time (change in velocity over change in time = acceleration).

Just as with velocity, there is something called instantaneous acceleration. Instantaneous means scientists measure your acceleration for a specific moment of time. That way they can say he was accelerating at exactly this amount at this point during his trip.

Extra credit!

• From the velocity-time graph or from your data table, create an acceleration-time graph. Show your work for how you calculated your acceleration.

• Analyze the graph/explain what your graphs means.

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Part IV Analyzing Graphs

ANALYSIS - to answer along with your graphs:

POSITION-TIME GRAPH:

1. Describe the motion of the car in terms of position.

2. Are there any parts of the graph where the car was traveling with uniform or constant velocity? How can you tell?

3. Label any constant velocities on your graph (include a key)

4. Are there parts of the graph that indicate that the car was accelerating (changing velocity over time)? How can you tell?

5. What is the relationship between the steepness of the slope of the graph and the velocity of the movement?

6. Where was the car’s velocity the greatest (Give specific points and label this on your graph – colors & a key help).

7. What is the average velocity of the car for the entire journey? How did you figure this out?

VELOCITY-TIME GRAPH:

8. According to the velocity-time graph, are there any segments when the car was undergoing uniform acceleration (constant)? How can you tell?

9. Calculate the average acceleration for any segments that appear to be uniform.

10. Describe any other useful information you gathered from analyzing the graphs.

Part V - CONCLUSION

(Written in paragraph form or numbered are both acceptable. Handwritten neatly is acceptable, typed is extra points on the rubric.)

Please use complete thoughts and sentences.

1. A great way to begin your conclusion is by writing a few sentences about what we are/were studying in class that DIRECTLY relates to the experiment. Be specific.

2. Describe the observed motion of your pull back car.

3. Compare how this observed motion relates to shapes of the curves and the calculated velocities and accelerations on the graphs.

4. Why are position-time graphs and velocity-time graphs useful for the study of motion?

5. What are the limitations of these graphs?

6. Explain any problems encountered during the experiment that could account for errors in the data. Include uncertainty of measurement somewhere on your data table ( (1/2 the smallest increment on your measurement tool +/- all your data points).

7. Describe any changes you would make to this lab in the future.

8. Describe how you can use the information learned in the experiment in the real world.

9. Feel free to add any other comments you feel are relevant to the lab (( extra effort).

What should I turn in?!

← This lab procedure sheet – your name/hypothesis should be on top (include the Part I instructions)

← Attach position-time, velocity-time graphs (acceleration-time for Extra Credit)

← Analyses for each graph

← Conclusion Questions

← Rubric

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