LAB 1: MOTION

Motion of objects can be described using displacement, velocity, acceleration and the relationships between them. In this lab you will be analyzing the motion of a soup or soda can as it goes away from the motion detector (CBR), hits an obstruction, and returns towards the CBR.

OBJECTIVES:

  1. Observe the relationships between displacement, velocity, and acceleration.
  2. Calculate the average velocity and acceleration over a time interval.
  3. Relate the type of motion to the displacement, velocity, and acceleration graphs.

MATERIALS:

1 CBR unit and connecting cable

1 TI-82 or 83 calculator

1 soup or soda can

DIAGRAM:

 

PROCEDURE:

1. If you have a TI83 plus, go to apps and select CBL/CBR. Select RANGER and skip to step 2 below. If you do not have a TI83 plus, connect the CBR to the calculator. Make sure the cable is completely pushed in. Load the program RANGER into your TI calculator from the RANGER.

2. Start the program RANGER on your graphing calculator.

4. Select the option SET UP from the MAIN MENU. Then choose NO for real

time by pressing enter. Set the time to about 5 seconds. Set the smoothing to HEAVY.
  1. One student should select START NOW on the graphing calculator and press ENTER. When the motion detector begins to click the data will be recorded by the CBR. Push the can away

    2. from the motion detector towards your partner. When the can reaches your partner, he should send it back towards the CBR. Stop the can when it reaches the starting point. Make sure there is sufficient time for the can to bounce off your partners hand and return towards the CBR.

  2. When the motion detector has stopped clicking, the CBR is done collecting data. . Notify the teacher when you are done with the equipment to be sure that your data is reasonable.
  3. Check the graph on the calculator to see which part of it reflects the motion of the can. Make a quick sketch of the DISPLACEMENT (POSITION) vs time graph. Press ENTER on the graphing calculator. From the SELECT GRAPH menu, select VELOCITY, and ACCELERATION to sketch the other two graphs, taking note of the time interval for which the motion of the can was recorded. Press ENTER after you have finished examining a graph to exit the graph.

8. When you have finished with the graphs, quit the program and note that the quantities are

recorded as lists L1 to L4 in the calculator. Press STAT and choose EDIT to examine the lists. L1 is the column for time, L2 for DISPLACEMENT, L3 for VELOCITY and L4 for ACCELERATION. You can send these lists to yours or your partners TI-82 or TI-83.

9. a) Find and record the time when the can began moving. You can tell by looking at the displacement column to see where the displacement begins to increase substantially and the velocity is no longer very close to 0.

  1. Find and record the time when the can hits your partners hand and turns around. You can tell by looking at the displacement column for the highest value and the velocity column to see where the sign changes from positive to negative.
  2. Find and record the time when the can stopped moving. You can tell by looking at the displacement column to see where the displacement begins to stay at about the same amount and the velocity becomes very close to 0.
  1. Record the section of data from the lists for the times when the can was moving away from the CBR, using the data for every 0.5 seconds from the beginning of motion (from part 9a) until the turn around time (from part 9b).
  2. Record the section of data from the lists for the times when the can head back towards the

CBR., using the data for every 0.5 seconds from the time the can turned around until it stopped (from part 9c).

 

DATA

Record the data for parts 10 and 11 on a table with the following headings:

time, displacement, s velocity, v acceleration, a.

CALCULATIONS

  1. Calculate the average velocity for the time interval from the time the can began to move away until it hit your partners hand using the data first and last displacements from part 10 of the procedure.
  2. Calculate the average acceleration for the time interval from the time the can began to move away until it hit your partners hand using the first and last velocities from part 10 of the procedure.
  3. Repeat calculations 1, and 2 for the time interval from the time the can began to return back towards the CBR until you stop it, using the data from part 11 of the procedure.
  4. Calculate the average speed for the entire trip using the displacement data for the beginning, turn around and ending times
  5. Calculate the average velocity for the entire trip using the displacement data for the for the beginning and ending times.

ANALYSIS:

 

  1. On your displacement verses time graph for the can, indicate by highlighting or brackets, the part of the graph that shows motion away from the CBR and label it AWAY. Do the same on your velocity graph.
  2. On the distance and velocity graphs, using brackets or another highlighting color, indicate the part of the graph that shows motion back towards the CBR and label it BACK.
  3. On the distance and velocity graphs, draw an arrow pointing at the part of the graph where the can is turning around and label it TURN.

    4. For AP students, the following are things to consider for your write up of the analysis. Do not limit yourself to these ideas. Make sure you consider the objectives of this lab in your analysis and conclusion. The analysis must be in paragraph form. Use numbers from the data and calculations to support claims.

     

    For regular students, answer the following questions. Use numbers from the data and calculations where appropriate to support your answers.

     

    QUESTI0NS:

  4. Are there any time intervals on the DISPLACEMENT graph during which the velocity of the can appears to be constant? How do you recognize those intervals?
  5. Now check the time interval from question 4, but by looking at the VELOCITY graph to see whether the velocity is truly constant. Explain how you can tell whether it is or is not constant.
  6. How do your calculations for the average velocities compare with the corresponding velocities recorded for parts 10 and 12 in the procedure?

    7. FOR AP ONLY: 7 - 10 are for AP only

  7. Label and show the time for the following on your displacement verses time graph:

    8. the point when the can begins to move

    the point when the can begins to slow down

    the interval for which the can is speeding up

    the interval for which the can is slowing down up

  8. Repeat part 7 for your velocity verses time graph
  9. Using the intervals from the time the can begins its motion to the end of the motion, do the following:
      1. approximate the instantaneous velocities for each time interval in parts 10 and 11 in the procedure using the displacement data.
      2. approximate the instantaneous accelerations for each time interval using the values from part a.
  1. For what time intervals is the average velocity close to the calculated instantaneous velocity of the can going away from the CBR? going towards the CBR?

CONCLUSION: The conclusion is a summary of what you learned from the experiment. Consider what the objectives of the experiment were. The conclusion may also include reasons for uncertainties and errors in the data, as well as suggestions to improve results.

Your lab write up should include the following sections in order:

Title, introduction, purpose or objectives, materials or apparatus, diagram with labels, procedure, data, sample calculations, results (calculations), analysis, and conclusion.

Diagrams, data, calculations, graphs, and tables need not be typed.

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