Group+3.1-2-EB

Procedure:
Time graphs
 * 1) Plug in USB motion sensor into computer.
 * 2) Open DataStudio and open “New Experiment”
 * 3) Open graphs for motion, velocity and acceleration.
 * 4) Run each scenario:
 * 5) No motion – stand still in front of motion detector
 * 6) Increasing speed towards – walk towards detector, getting increasingly faster
 * 7) Decreasing speed towards – walk towards detector, getting increasingly slower
 * 8) Constant speed towards – walk towards detector, staying at the same pace
 * 9) Increasing speed away – walk away from detector, getting increasingly faster
 * 10) Decreasing speed away – walk away from detector, getting increasingly slower
 * 11) Constant speed away – walk away from detector, staying at the same pace
 * 12) Analyze data, and determine idealized results

Ticker Tape 1. Set up spark timer with piece of ticker tape 2. Run each plausible scenario: a. No motion – do not pull tape through b. Increasing speed away – pull tape through, getting increasingly faster c. Decreasing speed away – pull tape through, getting increasingly slower d. Constant speed away – pull tape through, staying at the same pace 3. Analyze and interpret data

Data:
Good diagrams.

Analysis and Data Interpretation:


Please cut and paste questions/answers next time.

4. How can you tell that you changed direction on a...
 * Motion Diagram
 * On a motion diagram, the arrows represent direction. A change in direction of the arrow would indicate a change in direction.
 * Ticker Tape Diagram
 * This representation of motion cannot display a change in direction. This is because the tape that is fed through the instrument can only be inserted one way.
 * Position vs. Time Graph
 * You can detect a change in direction by a switch from a positive slope to a negative slop, or vice versa. For example, if one starts moving away from the censor the graph will show a positive slope, but when one starts moving towards the censor the graph will display a negative slope. This change should roughly form a V shape.
 * Velocity vs. Time Graph
 * When moving toward a censor points show up below the X axis. When moving away from a censor the points show up above the X axis.
 * Acceleration vs. Time Graph
 * When moving towards the censor, the peaks will become gradually shorter. When moving away from the censor, the peaks will become gradually longer.

5. How can you tell that your motion is increasing on a...


 * Motion Diagram
 * The length of the arrows represent speed on a motion diagram. Increasing motion is indicated by consecutive arrows becoming increasingly longer.
 * Ticker Tape Diagram
 * As motion is increasing, the dots on the tape will gradually show more space between them.
 * Position vs. Time Graph
 * As motion is increasing, the slope of the graph will become steeper. This is because for every second that passes, the moving object is getting farther from its original point.
 * Velocity vs. Time Graph
 * As motion is increasing, the graph will curve more steeply upwards because the speed is becoming faster per second increment.
 * Acceleration vs. Time Graph
 * As motion is increasing, this graph will also curve more steeply upwards because the acceleration is being increased as a result of the velocity.

6. How can you tell that your motion is decreasing on a...


 * Motion Diagram
 * The length of the arrows represent speed on a motion diagram. Decreasing motion is indicated by consecutive arrows becoming increasingly shorter.
 * Ticker Tape Diagram
 * As motion is decreasing, the dots on the tape will gradually show less space between them.
 * Position vs. Time Graph
 * As motion is decreasing the slope of the graph will become more gradual. This is because for every second that passes, the moving object is getting less farther from its original point.
 * Velocity vs. Time Graph
 * As motion is decreasing, the graph will curve more steeply downward because the speed is becoming slower per second increment.
 * Acceleration vs. Time Graph
 * As motion is decreasing, this graph will also curve more steeply downward because the acceleration is being decreased as a result of the velocity.

Discussion Questions:
1) What are the advantages of representing motion using a… a) Motion diagram- With a motion diagram it is clearly visible if the speed is increasing, decreasing or going at a constant rate. It allows us to also see the relationship between acceleration and velocity. b) Ticker tape diagram- The ticker tape diagram is straightforward. The dots clearly show that as the tape is pulled slower, the dots are closer together. This is an easy, visual way to compare speeds. c) Position vs. time graph- The position vs. time graph enables you to know where the moving object is relative to the sensor. d) Velocity vs. time graph- The velocity vs. time graph helps us understand how speed and motion are related. Also, it shows if an object is moving in a positive or negative direction. e) Acceleration vs. time graph- The acceleration vs. time graph shows if the change in velocity was positive or negative and describes motion in the terms of acceleration.

2) What are the disadvantages of representing motion using a… a) Motion diagram- The motion diagram does not measure the velocity or acceleration. It just depicts the general trend of them. b) Ticker tape diagram- There are disadvantages with the ticker tape diagram. It is not the most accurate way to measure the speed of the tape moving since there is no measure of time. Also, it can not show the movement of the tape toward it. c) Position vs. time graph- The position vs. time graph is effected by outside factors, which influences it. d) Velocity vs. time graph and acceleration vs. time graph- The disadvantage with using the velocity vs. time graph and acceleration vs. time graph is that they are too sensitive to movement. Human movements are not continuous and therefore there are small fluctuations, which get picked up by the sensors. These extraneous movements make it difficult to get an accurate graph.

3) Define the following: a) **No motion** is when an object is not changing its physical position or place b) **Constant speed** is movement at a fixed distance per time with no acceleration and unchanged velocity but changed position. c) **Increasing speed** is when the rate of advancement of an object gradually gets faster. d) **Decreasing speed** is when the rate of advancement of an object gradually slows down.

Conclusion
Although our results were not perfect, they represented the reality of motion. For example, no motion always showed a straight horizontal line. An additional example is that on the position graph, moving towards the censor always had a negative slope and moving away from the graph always had a positive slope. Even though our results were fairly accurate, there was room for error due to the procedure. We weren't able to perfectly execute constant speed, therefore those graphs could be slightly inaccurate. The motion censors also picked up many of our body parts individually, instead of our body as a whole. This could have led to fluctuation in the graph. For example, as we walked the censor may have picked up the motion or position of one leg at a time. After completing this lab, we can infer that even though distance, velocity, and acceleration are closely related, they are all different. This causes the three measurements to be affected differently by the same motion and direction. good

**Constant Motion Vehicle and Spark Tape** Hypothesis: The distance between the points, when graphed, will form a (generally) straight, diagonal line. The line will be straight and not curved because the speed of the CMV is constant and will bring through the same amount of tape each second.


 * 1) Rip off a piece of spark tape and attach it to a Constant Motion Vehicle.
 * 2) Feed the spark tape through the spark timer, and turn on CMV and timer at the same time. The CMV should be pulling the tape through and away from the timer.
 * 3) Measure the distance from point 0 to each point, and record each distance in a table.
 * 4) Graph about 20 points, or until a trend forms.

Diagram: wow, great diagrams! **Crash Problem** Hypothesis: The cars will crash when the slow car reaches 207.6 cm.


 * 1) Arrange 2 CMVs facing each other on a flat, even surface.
 * 2) Mark initial location of CMVs and measure distance between the 2 cars.
 * 3) Turn on both vehicles at the same time.
 * 4) Mark and measure the location where the vehicles crash
 * 5) Compare data to predictions.

Diagram:

media type="file" key="Long Crash.mov" width="300" height="300" media type="file" key="Crash.mov" width="300" height="300"

**Catch-Up Problem** Hypothesis: The fast car will catch up to the slow car when the 2 cars reach 212.3 cm.


 * 1) Arrange 2 CMVs, one behind the other, slower one in front.
 * 2) Mark initial location of CMVs and measure distance between the 2 cars.
 * 3) Turn on both vehicles at the same time.
 * 4) Mark and measure the location where the back car catches-up with the front car.
 * 5) Compare data to predictions.

Diagram:

media type="file" key="Catchup.mov" width="300" height="300"

Data
[|A Crash Course- Data.xls]


 * Calculations**

good to post. Also good to post screenshot.



**Discussion questions**

1) Why is the slope of the position-time graph equivalent to average velocity? The equation for slope is . The equation for velocity is . Since the y axis of the graph represents position (distance) and the x axis represents time, the slope and average velocity are the same value.

2) Why was it okay to set the y-intercept equal to zero? The y-intercept can be set to zero because there can not be a negative position relative to time in this experiment.

3.) What is the meaning of the R 2 value? In statistics, the R 2 is a value between 0.0 and 1.0 that describes "how perfect" the line of best fit depicts the data. For example, if the R 2 value is 0.0, knowing one X will not help you predict another X value at all. If the value is 1.0, every point falls exactly on the line of best fit, so knowing one X value will perfectly describe all the rest. 4) Where would the cars meet if their speeds were exactly equal? If the speeds were exactly equal, the cars would meet at the mid point of the distance traveled. For this lab if the speeds were equal, the cars would meet at 300 cm.

5) Sketch position-time graphs to represent the catching up and situations. Show the point where they are at the same place at the same time.

The point of intersection of the two lines (6.01 s, 212.3 cm) is where the two cars would be next to one another.



The point of intersection of the two lines (11.12 s, 207.6 cm) is where the two cars would crash.

6) Sketch velocity-time graphs to represent the catching up situation. Is there any way to find the points when they are at the same place at the same time?

The graph below shows the velocity in terms of the time each CMV was running. These were the velocities of the two machines during the catching up problem. With a velocity-time graph, there is no way to see the points when the two CMVs are at the same place at the same time. Because both of the cars' velocities start at 0 and continue at a constant speed for the full trial, there is no intersection or indication of catching up. A position-time graph would show the point of catching up clearly.

Excellent presentation. Just missing a Conclusion?