Group+7.1-2-EB

rachel and emily roshni and jillian
 * A Crash Course in Velocity - September 20th, 2010**
 * Due date: September 21th, 2010**
 * BY EMILY BURKE, ROSHNI KHATIWALA, RACHEL CASPERT, AND JILLIAN LAUB**

The purpose of this lab is to see our physics equations we use in world problems in actual stimulations. Actually visualizing these trials and eseeing how they work allows us to confirm the calculations we use.
 * PURPOSE**

When the cars are moving towards each other, it's expected for the collision to occur closer to the slower car. When the cars are moving in the same direction; the greater difference in the speed, the short the time for them to meet.
 * HYPOTHESIS**

1. Gather materials (slow car, fast car, spark timer and tape, masking tape). 2. Attach a strand of spark tape to the end of slow car with masking tape and place it through the spark timer. Let the car move for a few seconds as the spark timer records. Do the same with the fast car. 3. Number each dot on the spark tape as a 1/10 of a centimeter (spark timer was on 10 hertz, records a dot every 1/10 of a second). For both speed cars. 4. Measure and record the distance between each dot and the starting point at 0 for about 20 points. For both speed cars. 5. In an excel graph, graph all the points on a position v time graph. 6. Find the linear fit for both lines as well as the r^2. 7. Gather materials necessary for second part of procedure (tape, slow car, fast car, meter stick, measuring tape). 8. Place the two cars 600 cm apart facing each other. Let them both go at the same time and record how far each car travels until they reach each other. Repeat about 5 times. 9. Place the two cars 1 m apart, the slow car in front and the fast car in the back. Let the start at the same time and run until they meet up. Record the distance it took for the two cars to meet. Repeat about 5 times. 10. Solve both steps 8 and 9 algebraically and see if your observed data is similar to the algebraic numbers you solved for. If not similar, repeat the demonstrations until a similarity is seen.
 * PROCEDURE**

DATA:





__**DEMONSTRATION A (crash)**__ Speed of Car A: 18.4 cm/s Speech of Carb B: 12.6 cm/s (acquired from graph) (CRASH POINT)

__**DEMONSTRATION B (catch up)**__

__**DISCUSSION QUESTIONS**__

1. Why is the slope of the position- time graph equivalent to average velocity? Slope is calculated by doing the change in y over change in x. On our graph, this is equivalent to the change in position over change in time. Average velocity is change in distance over change in time so therefore it is the same.

2. Why was it okay to set the y-intercept equal to zero? In this experiment, the cars are only moving in one direction. There is no negative displacement, and so the y-value (the position) will always be above 0. Setting the y-intercept to any lower value is completely futile.

3. What is the meaning of the R^2 value? R^2 is the probability that future data will fall on the best fit equation line.

4. Where would the cars meet if their speeds were exactly equal? In a catching up problem, the cars would never meet if their speeds were exactly equal and if one started in front of the other. With equal speeds, the 2 cars would be moving at the same pace and therefore keep their same distance. If the front starts 1 meter ahead of the second car, at any given time, the front car will still be exactly 1 meter ahead.

5. Sketch a position-time graph to represent the catching up. Show the point where they are at the same place at the same time. The point where the two cars meet is at 4.25 seconds and 1.4 meters.

6. Sketch a velocity-time graph 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? You could find the point where they are at the same place, at the the same time if you were given the starting points. But with just this velocity time graph, you could not figure it out.

__**CONCLUSION**__

Our hypothesis was indeed correct, as proved by both the algebraic experiments as well as the real-life experiment we performed in class (refer to work as well as data to confirm).

One of our major sources of error was something beyond our control: an unfortunate situation where the batteries to one of our cars had been dying. We were completely unaware of this occurrence until the experiment was over, when Ms. Burns came over and looked at our data. We had assumed that one of the cars was just incredibly slower than the other (as intended). This made our trials extremely inconsistent with each other, as the battery died more and more with each run; the second car became exponentially slower until it eventually lost its ability to move. To keep the experiment as consistent as we possibly could with this unfortuante circumstance, we did not change batteries when we realized what what happening; this would've made our slow car much faster than it had previously been, which would completely wreak havoc on our entire data set, as well as out graphs.

In the future, this experiment should be changed to include a test run of both batteries. It should have a control speed, so that other will be able to quickly find out at the beginning of their experiment (not at the end) whether their variable speed is faulty or not. To ensure that our situation does not repeat again, every future group member should take responsibility to think of worst-case scenarios at the start of every lab; so that the consequences of not thinking again will not have to be reflected in their grade, as was the case with this lab.

The situation that this experiment describes is very relevant to real life. For example, especially on the highway, there are countless times that drivers come face to face with circumstances where they feel a need to overtake another car in front of them (in which case a catching up problem would be handy, to see if such an idea is actually plausible or not. Obviously, such a driver would not want to chance crashing into the other car, so he would try to avoid problems such as our first, crashing one).


 * MOTION LAB - September 13th, 2010**
 * Due date: September 14, 2010**
 * BY EMILY BURKE, ROSHNI KHATIWALA, RACHEL CASPERT, AND JILLIAN LAUB**


 * Graphs**


















 * Purpose**

Our purpose in this lab was to verify the affects of different kinds of motion on distance, acceleration, and velocity. We used no motion as our constant for the three graphs, and then we compared 2 directions of increasing motion, 2 directions of decreasing motion, and 2 directions of constant motion, observing the differences in our graphs of each. this isn't the purpose that I provided in the lab. Also, this goes first, not after the data.


 * Analysis & Data Interpretation**

i. There would be a straight horizontal line. i. There are no continuous dots. There are only the two dots where the spark is continuously burning. i. There is a straight line across the graph. i. There is a straight line across the graph. i. There is a straight line across the graph.
 * 1) How can you tell that there is no motion on a…
 * 2) Motion diagram
 * 1) Ticker tape diagram
 * 1) position vs. time graph
 * 1) velocity vs. time graph
 * 1) acceleration vs. time graph

2. How can you tell that your motion is steady on a… i. There would be a straight line with a positive or negative slope but not zero. i. The dots are close to evenly spaced. i. The line is either going up at a constant rate or down at a constant rate. i. The line goes up and down more in the beginning and end or middle. i. The line stays close to zero with a few bumps here and there.
 * 1) Motion diagram
 * 1) Ticker tape diagram
 * 1) position vs. time graph
 * 1) velocity vs. time graph
 * 1) acceleration vs. time graph

3. How can you tell that your motion is fast vs. slow on a… i. N/A i. Fast – the dots are very close together ii. Slow – the dots are farther apart from each other i. fast – the graph has a steeper slope, since you are covering more distance in a smaller amount of time ii. slow – the graph is more of a straight line i. fast – there are upside down V shapes pointing above the x axis ii. slow – there are V shaped lines pointing downward of the x axis i. fast – the line slopes up ii. slow – the line slopes down
 * 1) Motion diagram
 * 1) Ticker tape diagram
 * 1) position vs. time graph
 * 1) velocity vs. time graph
 * 1) acceleration vs. time graph

4. How can you tell that you changed direction on a… i. N/A i. A ticker tape diagram cannot change direction…it only goes one way. i. the graphs have different slopes (either negative or positive) i. most of the graph is either above the x axis, or below it i. most of the V shaped figures are either in the middle of the graph, or on the outermost edges
 * 1) Motion diagram
 * 1) Ticker tape diagram
 * 1) position vs. time graph
 * 1) velocity vs. time graph
 * 1) acceleration vs. time graph

5. How can you tell that your motion is increasing on a… i. The dots are farther apart i. The graph will start going down or up, depending on weather you are going away or towards the detector, at a flatter rate and then the slope will get steeper. i. The graph would slope upwards i. The graph will slope upwards because you are increasing your acceleration. 6. How can you tell that your motion is decreasing on a… i. The dots will become closer together i. The slope on the graph will become flatter i. The graph will slope downwards
 * 1) Motion diagram – NA
 * 2) Ticker tape diagram
 * 1) Position vs. time graph
 * 1) Velocity vs. time graph
 * 1) Acceleration vs. time graph
 * 1) Motion diagram- NA
 * 2) Ticker tape diagram
 * 1) Position vs. time graph
 * 1) Velocity vs. time graph
 * 1) Acceleration vs. time graph


 * Discussion Questions**

i. Easy and simple way to see the acceleration of an object i. You are able to tell where the object is in relation to the sensor i. It allows you to see if the object is moving in a positive or negative direction and if the object is speeding up or slowing down 1. It allows you to see if the change in velocity was positive or negative i. It only graphs the way an object moves away from the sensor, it is impossible to measure the object as it moves closer to the sensor i. It’s not the most accurate way of determining how fast an object was moving i. When recording with the motion sensor on the computer, it picks up the slightest changes of your legs motion and can have small inaccuracies throughout i. It does not show what the velocity of the object was at the time, only the change in velocity i. An object is at rest i. The object is moving at the exact same speed the entire time i. As time goes on, the object starts to move faster i. As time goes on, the object starts to move slower
 * 1) What are the advantages of representing motion using a…
 * 2) Motion diagram
 * 3) Ticker tape diagram
 * 1) Position vs. time graph
 * 1) Velocity vs. time graph
 * 1) Acceleration vs. time graph
 * 1) What are the disadvantages of representing motion using a…
 * 2) Motion diagram
 * 3) Ticker tape diagram
 * 1) Position vs. time graph
 * 1) Velocity vs. time graph
 * 1) Acceleration vs. time graph
 * 1) Define the following:
 * 2) No motion
 * 1) Constant speed
 * 1) Increasing speed
 * 1) Decreasing speed

**Evaluations and Conclusions**

//Error:// There were not many errors for this lab because there were no calculations to be done. Most of our errors probably came from the rate at which we moved closer to the sensor and the rate we moved further from the sensor. If we went at the same rate for every trial, the lines would be exactly correct.

//Implications for Further Discussion:// To make this lab error less we would have to know the exact speed to walk at the sensor or walk away. To address some of our possible errors, we would have done a couple things differently. For example we would have had multiple trials for each run to make sure that our data was verifiable, and we also would have had each person count their steps, and maybe mark the floor with their stating and end points. This would have been to make sure that we went exactly the same distance each time (to keep that as an unchanged variable in the experiement ), with only the acceleration and motion being different.

To better understand the way the technology and the every mechanics of cars, rockets, and similar transportation vehicles, it would be extremely useful for us to be able to understand the different kinds of motion.