Ani+and+Chloe

= Lab 3: Bombs Away = Date: 9/27 missing purpose

Hypothesis
One dot is made on the tape every 1/60th of a second, so the faster the tape is being pulled through, the more spread apart the dots will be. We believe the dots on the ticker tape will becoming increasingly spread apart from the beginning of the tape to the end. This is because the mass will not be falling at a constant velocity - the velocity will be increasing (toward negative infinity) because of the negative acceleration imposed by gravity (which is theoretically -9.8 m/s/s).

Materials
Spark timer, ticker tape, clamp, m-long measuring stick, 50 g mass

Procedure
1. Clamp ticker tape timer to the top of a cabinet door, or anything else, somewhere about 7 feet off the ground 2. Set the timer to 60 Hz 3. Feed the beginning of the ticker tape through the (direction: towards the floor) and attach the mass to the end of the ticker tape thats already through the timer 4. Turn on the timer and drop the mass, which will pull the ticker tape though the timer as it falls to the ground 5. Measure the distance from the beginning of the tape to each mark, and record in a table like the one below

heading on second column?

set y-intercept = 0, nice R^2

[[image:graph_distance_time_lab_3_ani_chloe.png]]
File:

Calculations
Finding acceleration (a) y= Ax 2 + Bx, y= A(t) 2 + B(t) d= Vit +1/2at 2 A = a/2 421.08= a/2 __842.16 cm/s/s=a__

Finding percent error




 * 842.16-981.00|/981.00 x 100 = 14.15% error

1. Does the shape of your graph agree with the expected graph? Why or why not? Yes, the expected graph of the distance in relation to time of the object would be a polynomial graph, the graph we got. The object started at rest, with a slope of zero, and accelerated to gravity’s velocity. The curve of the graph shows the increase in velocity (change in position based on time), and allows us to find the acceleration.

2. How do your results compare to that of the class? (Use Percent difference to discuss quantitatively.)

The average acceleration value for the class was 926.39 cm/s2. The percent difference between our value, 842.16 cm/s2, and the class average is the absolute value of the difference of the two values divided by the average of the two values times 100. In this case, the percent difference between the class average and our value is 9.5%. This is not very large, but the reason that it is not smaller may be because of how the outliers affected the mean. Some of the groups’ labs were conducted with error, as was ours. Our value may have been a little low due to us making the velocity of the object slower because of our hands releasing the ticker tape.

3. Did the object accelerate uniformly? How do you know? Yes, it accelerated uniformly because the acceleration was a constant. The position didn’t change uniformly because it was accelerating and its graph’s equation has an X^2. The velocity graph has an X, meaning the object’s velocity and position are both dependent on time. The acceleration, however, is always the same in the case of gravity. It is always -9.8 m/s/s

4. What should the velocity-time graph of this object look like? The velocity time graph should be a straight, diagonal line, with a positve slope (upward trend)

5. Write down the expected equation of the line from this v-t graph (use specific information from your x-t graph). The equation of velocity time graph would be: 842.16x + 7.1984 = y good 6. What factor(s) would cause acceleration due to gravity to be higher than it should be? Lower than it should be? Because the earth isn't a perfect sphere, the location where you drop mass will affect the acceleration due to gravity. Closer to the earth's equator (because of the principle that sticks you back in your seat on a roller-coaster) a tiny bit of earth's gravity is counteracted and the acceleration will be slightly less. Closer to the poles it will be slightly more. Altitude also affects the acceleration of gravity (AKA the weight of an object) the further from sea level, the lower the acceleration (and the "lighter" the object is). Local variations in the earth's topography and geology will affect the acceleration. Air resistance, depending on whether the air is moving with the falling object or against, can either increase the acceleration or decrease it. In addition, in the case of this lab, resistance may have been caused by our hands releases the ticker tape. This would have caused the acceleration to be lower than gravity. On the other hand, the acceleration could have been higher than gravity due to someone giving the tape a slight pull through the ticker machine, making the tape travel more quickly through the machine.

Conclusion
Our equation worked for the most part. The object was to figure out the acceleration of gravity, which we knew was -9.8 m/s/s. In terms of cm/s/s, which is what measurement we used, the theoretical acceleration should have been 981 cm/s/s. Our 14% error was due to how we conducted the experiment. Because our amount was lower than the theoretical value, that means the acceleration of our object was slightly slowed. Most likely, because we were guiding the ticker tape through the detector, this is where the error occurred. By guiding it with our fingers, we may have slowed the tape, therefore slowing the mass's free fall acceleration and making our 'value' of gravity lower. implications?