RJD+Acceleration+Lab

=Accelerated Motion Lab= 10/26/09


 * Participants**: Jill, Rachelle, and Drew.
 * Purpose**: The purpose of this lab is to determine the acceleration of (1) a hoverpuck traveling across a flat surface and (2) a free-falling mass (1Kg and 500g).


 * Brief Description of Experiment**: In this lab we took an object (Hoverpuck, 1Kg or 500g mass) and taped it to a tape timer. A tape timer is a device used to place marks on a piece of paper every 1/60 of a second. As the tape is pulled through the device by a moving object, the marks indicated the position of the object at intervals of 1/60 of a second. First we attached the tape timer to a hover puck and pushed the puck across the table (about 2 meters long). As we did this, marks were made on our strip of paper. We then did the same thing for a 1Kg mass and a 500g mass, except we dropped these from the ceiling which was about 2 meters as well. We then took our three different strips of paper and measured the distance from the starting mark, to each point on the paper. Those measurements would give us the information needed to find the acceleration of each object.
 * Data**:

Velocity Graph Equations: 1 Kg Mass Dropped from 2m: delta( change in position) /(1/60) 500g Mass Dropped from 2m: delta( change in position) /(1/60) Hover Puck across table for 2m: delta( change in position) /(1/60)
 * Sample Calculations:**

Position Over Time Graph: cm/sec

Percent difference: (your value - accepted value)/ your value * 100

speed = distance / time ||
 * //Speed calculation// || The speed in meters per second was calculated by taking the measured distance in meters and dividing by the time elapsed in seconds.
 * Results**: The purpose of this lab was to determine the acceleration of a hoverpuck traveling across a flat surface and the acceleration of a free-falling mass. From the data we collected we concluded that the accleration of the 500g weight was 9.167m/s/s and the acceleration of the 1kg weight was 9.347m/s/s. The acceleration of the hoverpuck was 1.68m/s/s when being push slightly and then -0.2241m/s/s when no force was being added to it.

**1. Which objects that you studied were clearly accelerating? How can you tell by looking at the motion of the objects? How can you tell by looking at the position vs. time graph? How can you tell by looking at the velocity vs. time graph?** The 1Kg mass and the 500g mass that was dropped from as high as possible were the objects that were clearly accelerating. You can tell because as these objects were dropped to the ground, the points on the paper made by the tape timer are spaced farther apart from eachother. Also, on the position vs. time graph, both of the lines for these objects are shaped like a parabola indicating they started off slowly increasing their distance traveled and then increasing in distance traveled in a shorter amount of time. On the velocity vs. time graph they both have generally linear lines which indicates that the objects' speeds' are increasing at a constant rate (or accelerating).
 * Lab Questions**:

**2. Which objects that you studied were not accelerating/ were accelerating slightly? How can you tell by looking at the motion of the objects? How can you tell by looking at the position vs. time graph? How can you tell by looking at the velocity vs. time graph?** The object that was not really accelertaing/ was only accelerating slightly was the hover puck. You can tell because the tape for the hoverpuck had points that were spaced out evenly, and as this object moved across the table, gravity wasn't pulling it to the ground and there wasn't any other force slowing it down or speeding it up. On the position vs. time graph, its line looks linear which indicates that it was moving the same distance every second (at a constant rate) and not accelerating. On the velocity vs. time graph the line slowing increases but then evens out to almost a horizontal line. This indicates that as we pushed the object to make it move, its velocity slowly increased, but when we were no longer pushing the object its velocity didn't change as much and began to slowly decrease. This means the hoverpuck began to slow down as we were no longer pushing it or having a force act upon it.

**3. What was the value of the acceleration of the 1kg object? Can you find a relevant value to compare this to for a “free-falling object” near the surface of the earth? How do your values compare (% difference)? Follow-up: If you also did a 100g object, what was the acceleration and how does this compare (% difference)? The value of the acceleration of the 1Kg object was 934.7 cm/sec/sec (about 9.347 m/s). ** This number is relevant to gravity which is the downward acceleration of a falling object and it has been calculated to be 9.8 m/s. (9.347 - 9.8/ 9.347 * 100 = -4.8% is the percent difference) We also did a 500g mass which had an acceleration of 9.167 m/s. (9.167 - 9.8/ 9.167 * 100 = -6.9% is the percent difference).

Negative acceleration just means that an object is slowing down.
 * 4. What is meant by a negative acceleration?**

Our objective was to find the acceleration of a falling object and a hoverpuck. From the experiment we found that the acceleration of the falling objects was around 9.8 m/s which is the calculated acceleration value for gravity. Also, the hoverpuck had a fairly constant acceleration proving that it was moving at a constant rate. From this information we would say this experiment was fairly accurate. Our data is not perfectly accurate for the falling objects because even though we tried to drop our objects from 2 meters it may have been slightly lower or higher. For the hoverpuck we had to push it to in order for it to move across the table so when we pushed it the acceleration increased and evened out when we were no longer pushing it. Lastly our measurements for each point on our strips of paper may not have been accurate because they were so close together and hard to record. We could improve our data by dropping our objects from something like a table which would have an exact height. We could also do several trials of each object to and record the data several times and find the average accelerations.
 * Conclusion**:

//Don't forget to link to your lab report from the lab reports page and to include a link to your lab report in your reflection.//