Motion in Air Investigation

Task:

Design an investigation into a factor that affects the flight of an object in the air

Background:

A projectile is any object released into the air. When is in the air the object starts to release because of several factors.

Factors that affect the flightof anobject in the air:

The object: Shape and Size. If the shape or the size of the projectile vary, also will do it the air resistance so, this means that the projectile will travel less distance.

The Motion: Velocity and Inclination to Flow. The projectile has to travel at the same velocity and with the same inclination so the time cannot vary, but we are changing the distance we strech the elastic band so the velocity will vary.

The air: Mass, Viscosity, Compressibility, Gravity, Air Resistance. The gravity is the same because we make the experiment in the same place with the same gravity. The mass and the viscosity will be the same, so the projectile will have the same size and shape.

3 equations related to motion:

Vf = Vi + at: To calculate the final  of a projectile, we need to plus the initial velocity to the multipllication of accelerationper time.

Vav = (Vi + Vf)/2: To calculate the average velocity we need to plus the initial velocity to the final velocity and divided all into 2.

T= (Vf-Vi)/2: To calculate the time you have to subtract the final velocity into the inicial velocity and divided all into the acceleration.

Research question:

How does changing the force of release affect the distance travelled of a projectile in motion?

Hypothesis:

According to my background, I believe that depending how do you strech the elastic band, it will reach more or less distance. If you strech the elastic band 15 cm this means that you are putting a lot of force in the projectile and it will reach more distance. If you strech the elastic band 5 cm you are not putting many force in the projectile, so, it will reach a very low distance.

I will use the formula of the initial velocity to prove that when we strech more distance the elastic band, the distance is higher so the initial velocity will also be higher because the mass of the projectile doesn´t vary in any tests. Formula of initial velocity= Vf- at.

The shape of the projectile always will be the same, so the air resistance will always be the same and it wouldn´t affect directly to the experiment.

Variables:

Independent variable: Distance we strech the elastic band, which will be measured in centimeters using a ruler.

Dependent variable: Distance the projectile travels measured in meters using a tape measure.

Controlled variable: The surface area of the projectile, I will control it using the same projectile with the same area to all tests.  The air resistance, gravity, I will control it because I will make the experiment in the same place with the same gravity, 9,8 m/s2. The elastic band, I will use the same elastic band for all tests. The two sticks and the position of the base, so the sticks offer the same resistance. The distance between both sticks measure in cm using a ruler.

List of materials:

-          Elastic band

-          Two supports (sticks) of wood

-          Plastecine

-          A knife

-          Ruler

-          Measure tape

Method:

1.       Cut using a knife a piece of clay

2.       Measure using a ruler the distance between the two sticks and set the elastic band in the sticks.

3.       Pull the rubber band back 5 cm, 7, 9, 11, 13 and 15 cm (measure with the ruler the distance). 

4.       Throw the ball of clay and measure with the measure tape the distance it has travelled.

5.       Collect all the data in a table to make a graph.

6.       Repeat the same steps 3 times with all the different distances to get accurate results.

Table for the results of the distance the projectile after throwing it at different distances (of the rubber band)

Distance of band (where it is placed to were the projectile is) in cm
Times repeated		5	7	9	11	13	15
	1	19	132	379.5	515	544	567.5
	2	23	145	381	530	535.5	560.5
	3	28	139	375	519	540	572
	Average	23.333	138.666	378.5	521.333	539.833	566.666

Graph for the distance the projectile after throwing it at different distances (of the rubber band)

Evaluation

Although it was an easy experiment, we know that the results are not very reliable because the technique we used to through the ball was not very scientific.

Firstly the plasticine deformed with the air resistance, so in the last test the ball will have less volume than in the first one. To solve this problem, we will use a marble that doesn´t deformed because is made of plastic.

Other problem was that when we threw the balls, the angle was not the same for all tests, this could affect to our results so the graph is not completely correct. This happens because we pull back the elastic band and our hands probably moved. A solution to this problem would be to write a mark in the wall to know the distance we through the projectile from the floor, so we only have to pull back the elastic band to the mark on the wall and the angle will always be the same.

Moreover, the traveling distance we measure is probably not correct 100%. From 7 cm, the ball travels far from where we was and we could not calculated with our ruler because was only from 30 cm so we calculated the distance of one tile and we multiplied it with the tiles the ball travels. For example, if the ball goes 10 tiles far from where we threw the ball, we multiplied the distance of one tile by 10. This was not a very scientific technique, so for the next time we will use a meter to measure the distance with accuracy.

To conclude, I would say that our principal problem is the measurements that are not accuracy and affects directly to our graph so is the point we need to improve. 

 Conclusion

Our results have been good, as when the rubber band is at more distance, the tension is higher so it will go further, which means that the initial speed will be higher. We can see in our graph that the last values don’t have so much difference between them than the ones at the start, this can be due to the rubber band use, and that through the experiment it doesn’t have finally the same tension. Our hypothesis has been proven, so how longer is the distance of the end of the rubber band to where it is placed, the more distance it will travel (the ball). This could be a directly proportional relation, but I think that for so exact values is needed a higher quality experiment.

Not all of the equations or formulas included in the background (in the research part of the investigation) were used in our experiment or were completely relevant, but I think it is better to have them as a guide and to be able to relate different concepts. The one which is linked to the initial velocity is very important, because that is just what we are changing in our experiment; the initial velocity changing the tension of the band so that it shoots the projectile harder.

In my opinion, the method was well stated and clear. If you follow this method as it says you will have good results in your experiment. Having a clear, structured method is a very important part in science.

References:

Citycollegiate.com, (2015). EQUATIONS OF MOTION-FIRST EQUATION OF MOTION-SECOND EQUATION OF MOTION-THIRD EQUATION OF MOTION. [online] Available at: http://www.citycollegiate.com/kinematicsXb.htm [Accessed 31 May. 2015].

Exploration.grc.nasa.gov, (2015). Factors that Affect Aerodynamics. [online] Available at: http://exploration.grc.nasa.gov/education/rocket/factord.html [Accessed 32 May. 2015].

Physics.info, (2015). Motion - The Physics Hypertextbook. [online] Available at: http://physics.info/motion/ [Accessed 15 Jun. 2015].

Lab Sesion 3 - Boiling point elevations for solutions of benzoic acid in acetone

Objective – To investigate the relationship between the molality and the boiling point of a solution.

Hypothesis:

When more solute (benozoic acid) we add to the acetone, the vapor pressure of the solvent is less than the vapor pressure of the pure solvent. The boiling point of a solution will be higher than the boiling point of the pure solvent because the solution (which has a lower vapor pressure) will need to be heated to a higher temperature in order for the vapor pressure to become equal to the external pressure. In this case, when more benzoic acid we have in the solution, more it will take to boil.

Table:

Mass of benzoic acid in solution (g)	Molality (mol/kg)	First run - Boiling point (oC)	Second run - Boiling point (oC)	Average boiling point (oC)	Change in boiling point compared to pure acetone (oC)
0	0	56.0	56.4	56.2	0.2
0.5	0.82	58.8	58.0	58.4	2.4
1.0	1.64	60.7	60.5	60.6	4.6
1.5	2.46	51.5	51.3	51.4	5.4
2.0	3.28	65.3	64.7	65.0	9
2.5	4.0	67.1	67.1	67.1	11.1

Evaluation:

We think it was a complex experiment because we confused many times with the tested and this makes that we couldn´t finished correctly the experiment.

The first problem was to calculate the measurement because we calculated using the eye line and this is not very accurate. A good solution is to change the mL into grams so we can calculate it in the balance and we have the exact measure, but this will takes us lot of time and it would slow down our experiment and we don´t have so much time.

When we were going to make the graph using the table, we saw that there were two wrong results in the table, the one using 1.5 mass of benzoic acid in solution. To don´t put this mistake in the graph we remove it and we don´t use it in the graph.

Other big problem was when the liquid evaporate we lose solution and this affect directly to the project and when the acetone boils, and starts to grow bubbles, we also lose liquid and the concentration. We have to take care and being precise when we calculate the temperature because it could react and we can lose liquid because of the bubbles or if it boils, the acetone will evaporate and we also lose liquid, we will have other results.

Also a problem was when we poured acetone in the bunk and this affected in the temperature so we could have different results. To solve this problem, we have to be precise with the temperature because we know that the bunk is not going to be at the temperature we have, so a good idea would be, turn to the higher temperature and pay attention to the thermometer and the temperature it marks when it reacts. Finally we have to be precise with the temperature because when we get the test tube outside from the bunk the temperature will cool down, so we have to see when it reacts and see the correct temperature when the test tube is in the bunk.

Conclusion:

We said in the hypothesis that the more solute (benozoic acid) we add to the acetone, the vapor pressure of the solvent is less than the vapor pressure of the pure solvent, so the boiling point of a solution will be higher than the boiling point of the pure solvent.

In the graph we can see that with more concentration, the boiling point will increase, the line grows up. The function is directly proportional because when x grows also y grows.

When we finished the experiment and we get all the data we could prove that the hypothesis was correct because the boiling point of a solution will be higher than the boiling point of the pure solvent.

References:

Chemspider.com, (2015). Benzoic acid | C7H6O2 | ChemSpider. [online] Available at: http://www.chemspider.com/Chemical-Structure.238.html [Accessed 21 Feb. 2015].

Webbook.nist.gov, (2015). Acetone. [online] Available at: http://webbook.nist.gov/cgi/cbook.cgi?ID=67-64-1&Type=IR-SPEC&Index=QUANT-IR,0 [Accessed 21 Feb. 2015].

Lab Sesion 2

Objective: To relate a physical property to the intermolecular forces found in different chemicals.

Theoretical background: Many physical properties are related to the types and strength of intermolecular forces found in a chemical substance.

In this lab session we will look at the rate of evaporation, surface tension and viscosity.

Hypothesis: We are timing how much it takes to a little ball to go down through different chemicals. The chemicals have different intermolecular forces which can make them have different structures, which means different levels of viscosity.

Group 1 - similar molecular mass
Name	Molecular Mass	Time 1	Time 2	Time 3	Time average
Diethyl Ether	74,12	0,38	0,41	0,25	0,346666667
Pentane	72,12	0,41	0,32	0,34	0,356666667
Butanol	74,12	0,5	0,37	0,47	0,446666667
Propanoic acid	74,08	0,75	0,54	0,5	0,596666667
Group 2 - Acetates
Name	Molecular Mass	Time 1	Time 2	Time 3	Time Average
Methyl Acetate	74,08	0,69	0,69	0,55	0,643333333
Ethyl Acetate	88,11	0,59	0,75	0,59	0,643333333
Propyl Acetate	102,13	0,44	0,66	0,46	0,52
Butyl Acetate	116,16	0,37	0,5	0,41	0,426666667

Types of IMF´s and structure

Name	Structure	Type of IMF´s
Diethyl Ether		Van der Waal
Pentane		Van der Waal
Butanol		Van der Waal Dipole
Propanoic acid		Van der Waal Dipole

Name	Structure	Type of IMF´s
Methyl Acetate		Van der Waal
Ethyl Acetate		Van der Waal
Propyl Acetate		Van der Waal
Butyl Acetate		Van der Waal

Evaluation:

The first problem was that the balls of clay where very heavy to the viscosity of the components, this means that the ball goes down very quickly and we couldn´t see when it touch the bottom of the test tube, so we couldn´t measure the time. To solve this problem we made smaller balls of clay and we enveloped the balls in silver paper so the balls will occupies more space but the density is less so the ball will take more time to get down.        

Other problem is the time, we don´t know the exact moment when the ball touch the component and when it touch the bottom of the test tube so we cannot know when to start the stop watch and end it, in this way, the experiment is not completely correct because the results are approximated. The solution is to record when we drop the ball and we will know the exact moment when the ball reaches the end of the test tube, we get the time from the video.           

Finally, we would say that one important problem that slowed us in the procedure of the experiment was that there were many different components and we confused many times, we need more concentration on it and we have to be more organised to make a better experiment.

References:

Chemguide.co.uk, (2015). intermolecular bonding - van der Waals forces. [online] Available at: http://www.chemguide.co.uk/atoms/bonding/vdw.html [Accessed 25 Feb. 2015].

Science.uwaterloo.ca, (2015). Intermolecular Forces. [online] Available at: http://www.science.uwaterloo.ca/~cchieh/cact/c123/intermol.html [Accessed 25 Feb. 2015].