Sean+and+Phil+Free+Fall+Lab

__**Free Fall "Bomb's Away" Lab**__ Objective: To find the acceleration of a falling body and compare our findings with the known value of 980cm/s^2

Hypothesis: When we drop our mass we will see an increasingly larger distance between the dots the longer it falls due to gravity's acceleration. The acceleration we get from our calculations will be approximately 980cm/s^2.

Procedure:

1. Set the spark time to 60 hertz. 2. Clamp the timer to the top of a door. 3. Cut a piece of spark tape slightly shorter than the height of the door. 4. Feed the piece of paper through the spark timer. 5. Attach the object using tape to the spark tape. 6. Turn on the timer and let the object fall. Make sure it does not hit anything except the ground. 7. Measure the distance between each dot on the spark tape. 8. Record the data in an excel spreadsheet. 9. Make a position-time graph in excel. 10. Calculate the acceleration due to gravity.





great results

Calculations: Percent Error = |981-855.92/981| X 100% = 12.8% error. time = dot# X 1/60 t(15) = 15 X 1/60 = .25s

Accleration:

y = 427.96x^2 - 13.396x y = Ax^2 + Bx d = 1/2at^2 + Vit A = 1/2a 427.96 = 1/2a a = 2 * 427.96 a = 855.92 m/s/s

Discussion Questions:

1. Does the shape of your graph agree with the expected graph? Why or why not?

The shape of our graph is what was expected: a positively curved line. This is because the object is accelerating at 9.8 m/s and so its velocity is increasing. With increasing velocity, the distance from the starting point becomes further and further, resulting in a curved line.

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

Percent Difference = |855.92-874.426/10.86| = 1.7% difference. Our results were quite close to the average class value.

3. Did the object accelerate uniformly? How do you know?

The object accelerated uniformly because as it fell, the acceleration due to gravity was always 9.8 m/s/s. Acceleration due to gravity never changes. circular argument.

4. What should the velocity-time graph of this object look like?

Since the acceleration is constant, the v-t graph should be positively sloped.

5. Write down the expected equation of the line from this v-t graph (use specific information from your x-t graph).

In a v-t graph, the slope of the equation is the acceleration. Therefore, the equation would be: **y = 855.92x**

6. What factor(s) would cause acceleration due to gravity to be higher than it should be? Lower than it should be?

Several factors could contribute to acceleration due to gravity being higher than it should be. One factor could be incorrect measurements. not a valid source of experimental error Another could be if something caused the object to accelerate in addition to gravity's acceleration, for example, if some sort of pulling force was applied to the object. Friction encountered when the tape was running over the door and through the spark timer would cause the acceleration due to gravity less than it should be. Incorrect measurements could also result in acceleration being less than acceleration due to gravity.

Conclusion: Part I, Results: <-- please don't write this... the conclusion should flow essay-like. Our results corresponded well with our hypothesis. Our ticker tape showed the acceleration through the gradual increase in space between the dots. After calculating our data, we found that our mass accelerated at 855.92cm/s^2. This is very close to the class average of 874.426cm/s^2.

Part II, Error: In this lab, there was not too much room for error. The reason why our acceleration as well as the class' acceleration was about 100-150cm/s^2 was due mainly to the unavoidable hindrance of friction in the experiment. Through the entire time the mass was falling, the ticker tape connected to it was running through the spark timer and rubbing against it, creating a reasonable amount of resistance.

Part III, Implications: Knowing the acceleration due to gravity of an object can be important in real life. For a supply helicopter, they need to know the velocity of their falling package, for perhaps if it hits the ground with too great a velocity, its contents may be damaged or destroyed. The pilots would be able to calculate the velocity by using an equation including the known -9.8m/s^2 value of acceleration due to gravity.