Motion in Air- Pepe Joly, Victoriano Valpuesta, Miguel Montaño and Miguel Martinez

Motion

Research Question:

How does the shape of two groups with different shapes each affect the flight of plasticine when 
being catapulted into the air?

Background Information:

Free fall is a special type of motion in which the only force acting upon an object is gravity. Objects that are said to be undergoing free fall, are not encountering a significant force of air resistance; they are falling under the sole influence of gravity. Under such conditions, all objects will fall with the same rate of acceleration, regardless of their mass. (Physicsclassroom.com, 2015). That explains why a 1000 kg elephant falls at the same speed as a 1 kg mouse.

A = F/M

If Newton's second law were applied to their falling motion, and if a free-body diagram were constructed, then it would be seen that the 1000-kg baby elephant would experiences a greater force of gravity. This greater force of gravity would have a direct effect upon the elephant's acceleration; thus, based on force alone, it might be thought that the 1000-kg baby elephant would accelerate faster. But acceleration depends upon two factors: force and mass. The 1000-kg baby elephant obviously has more mass (or inertia). This increased mass has an inverse effect upon the elephant's acceleration. And thus, the direct effect of greater force on the 1000-kg elephant is offset by the inverse effect of the greater mass of the 1000-kg elephant; and so each object accelerates at the same rate - approximately 10 m/s/s. The ratio of force to mass (Fnet/m) is the same for the elephant and the mouse under situations involving free fall.

This ratio (Fnet/m) is sometimes called the gravitational field strength and is expressed as 9.8 N/kg (for a location upon Earth's surface). The gravitational field strength is a property of the location within Earth's gravitational field and not a property of the baby elephant nor the mouse. All objects placed upon Earth's surface will experience this amount of force (9.8 N) upon every 1 kilogram of mass within the object. Being a property of the location within Earth's gravitational field and not a property of the free falling object itself, all objects on Earth's surface will experience this amount of force per mass. As such, all objects free fall at the same rate regardless of their mass. Because the 9.8 N/kg gravitational field at Earth's surface causes a 9.8 m/s/s acceleration of any object placed there, we often call this ratio the acceleration of gravity. (Physicsclassroom.com, 2015).

Hypothesis:

The time for the more flat ones to hit the floor will be greater than the time for the least flat ones due to the space covered that will make it have more air resistance.

Variables:

Independent: The diameter of the pieces of clay.

Dependent: The time it takes for the pieces of clay to hit the floor.

Control: The diameter of each piece of clay, the height at which they are dropped and lastly the force of gravity (9.8m/s), which will always be constant, without me being able to control or change it. I will also put no force into throwing them, I will just drop them without adding force.

Materials:

• 5 pieces of clay. The diameters will be: 4, 4,5, 5, 6 and 7,5 cm.
• A ruler to measure the diameters of the clay.
• Stopwatch to time the falls of the pieces of clay.
• Laptop to write the results in (in a table)
• A weight to measure the mass of the piece of clay

• Someone extra will be needed to either stay down to time the falls or stay up and throw them.

Method:

1. Go to the third floor of the school while your partner waits outside with the stopwatch.
2. Start dropping them out from a window. Make sure you throw them in such a way in which you are holding them with the flat sides facing up and down and do not put any extra force into throwing them.
3. After you drop each one, the person that is in the street with the stopwatch should start timing as soon as you drop the clay, and stop timing once it hits the floor. If it hits an object while going down, it must be repeated.
4. Make sure you know all the times to write them down after they hit the floor.
5. Repeat all the steps above again for more accurate results five times.
6. Repeat the experiment with the others measurements
7. After that, put the results into a table and a graph to compare them.

Diameter	Time #1	Time #2	Time #3	Time #4	Time #5	Average
4 cm	1.25 s	1 s	1.12 s	1.17 s	1 s	1.108 s
4,5 cm	1 s	1.20 s	1.3 s	1.14 s	1.17 s	1.162 s
5 cm	1.12 s	1.35 s	1.1 s	1.24 s	1 s	1.162 s
6 cm	1.75 s	1.3 s	1.34 s	1.1 s	1.62 s	1.422 s
7,5 cm	1.64 s	1.7 s	1.54 s	1.12 s	1.7 s	1.54 s

Graph:

Evaluation:

• We can not measure the exact mass of the pieces of clay, there might be some difference due to the scale is not as accurate as it should be according to get the exact mass, to solve this problem, i recommend to do the average of weight of the different repetitions.

• At the hour of measuring the diameter of the piece of clay, we might not get the exact measurement due to the lack of precision of the rulers we use in the lab, for that reason, i recommend to use a different and accurate measure object, however, it will difficult to get the exact measurement, i leave a image of an accurate ruler

• At the hour of doing the method, we have put an exact measurement of the height of throwing the clay, however, if another guy wants to make this experiment, he/she/them might find that they don't have the exact height as us, to solve this problem i recommend that they reach a similar height, the results will slightly vary though

Conclusion

In conclusion, our hypothesis, which proposed that the more flat ones will spend more time to hit the floor than the least flat ones (when talking about diameter), has been proved. As a result of the space covered in the air, we concluded that as the diameter increased, the time it took for it to reach the floor increased too. This can be proved as the average results for the object with a diameter of 4 cm are lower, as we are talking about time, than the results for the object with a 6 cm of diameter.

Bibliography:

· Mypages.iit.edu, (2014). The Free Fall Experiment. [online] Available at: http://mypages.iit.edu/~smart/martcar/lesson2/free-fall-experiment.html [Accessed 23 May. 2014].

· Physicsclassroom.com, (2014). Kinetic Energy. [online] Available at: http://www.physicsclassroom.com/class/energy/Lesson-1/Kinetic-Energy [Accessed 23 May. 2014].

·         Es.video.search.yahoo.com,. (2015). Tennis Ball Physics Experiment. Retrieved 27 April 2015, from https://es.video.search.yahoo.com/video/play;_ylt=A2KLqIkZITZVC1UA0Srk0olQ;_ylu=X3oDMTByZWc0dGJtBHNlYwNzcgRzbGsDdmlkBHZ0aWQDBGdwb3MDMQ--?p=experiment+about+changing+the+flight+of+an+object&vid=90bf265ca9f575bc31b6cedd128b915f&l=2%3A25&turl=http%3A%2F%2Fts4.mm.bing.net%2Fth%3Fid%3DWN.pMjcxhZmhnrDguu%252fdwvFyg%26pid%3D15.1&rurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DeUTKeGY8_0A&tit=Tennis+Ball+Physics+Experiment&c=0&sigr=11bllcq84&sigt=10u5nguqa&sigi=121m3nr27&age=1346256000&fr2=p%3As%2Cv%3Av&fr=yhs-Lkry-SF01&hsimp=yhs-SF01&hspart=Lkry&type=YHS_SF_1600&tt=b

·         Wikipedia,. (2015). Gravity of Earth. Retrieved 27 April 2015, from http://en.wikipedia.org/wiki/Gravity_of_Earth