Motion Lab Report

Carlos Pita
Aurora Martínez
María Victoria Rodríguez
Beatriz Pérez

RESULTS

Aluminium paper ball: 3,54g

The elastic band was stretched 10cm

	Table to show the distance the ball reaches (m)
DEGREES (º)	TRY 1	TRY 2	TRY 3	AVERAGE
0	2,80	2,73	2,94	2,82
20	3,80	3,91	0,80	2,84
45	9,10	8,90	9,90	9,30
60	5,10	5,20	7,20	5,83
80	3,00	2,80	2,30	2,70

Conclusion: As the graph and table shows the optimum angle would be 45º as it is when the ball reached its maximum length. If we take into account the anomalies as for example would be 0.80 metres at 20º the optimum angle will also be 45º. The yellow line shows this peak observed in the graph.

Also in the graph we can observe differences between the first two attempts and attempt 3 which probably is when we committed some mistakes as there is a huge difference from the lowest value to the highest value: from 0.80 to 9.90 (this difference is not presented in attempt 1 neither in attempt 2).

Afterwards the shots of 60º reach much higher distance than the others. In addition to this the other angles have lengths quite similar.

Also to obtain clearer conclusions it could have been a good idea to use different masses for the aluminium ball and to change the length of stretching the rubber band.

I conclude that majority of the experiment was well done as it resulted the optimum launching angle was the one researched.

We can determine the range of a projectile (displacement in horizontal direction) through the equation R . R is the range of the projectile and vi is the initial velocity.  is the launch angle and g gravity. Knowing the distance reached of the projectile could be very interesting when changing the angle of release or the speed. If we increase the launch speed, the range will increase. However, if we increase the angle of release, the range will be very low.

R= 10,2 meter.  We observe how 45º is the optimal launch angle as 10,2 is very close to the result where we obtained the higher range, 9.90 m.

Evaluation: We had some problems during the development of the experiment. Firstly, we didn’t exactly know how to make the object throw the ball, but finally we learned how to place the materials to throw the ball correctly. We also had timing problems; as we spent too much time learning how to work out the catapult, we didn’t had time to throw the ball 5 times, but instead we did it 3 times, therefore our results are not as accurate as we wanted them to be. We could have obtained a more reliable catapult from a specialised shop, however it would have cost us too much money. Another problem we had was that the clamps did not stay still, so it ended up influencing how the ball reached, therefore a solution for this would be either use something else such as a specialised device or make sure it stays still by holding it ourselves, as we did not know any form to attached them more securely without doing it ourselves. In addition, the ball was deflected back when it reached the ceiling, so as a solution for this we had to go somewhere outdoor, such as the playground. Finally, in more than one occasion we might have measured the length which the ball reached at the second bounce instead of the first, however we do not think that this human error has other solution rather than paying more attention to the ball. In fact, if we had used a camera maybe we could record distance more accurately.

References:
General Launch Angle. (2014). Boundless. Retrieved from https://www.boundless.com/physics/textbooks/624/two-dimensional-kinematics-3/projectile-motion-42/general-launch-angle-229-6255/
Physicsclassroom.com,. (2015). Maximum Range. Retrieved 16 April 2015, from http://www.physicsclassroom.com/mmedia/vectors/mr.cfm

Vista, T. (2015). Projectile Motion Formula | Formula for Projectile Motion | Formulas@TutorVista.com. Formulas.tutorvista.com. Retrieved 16 April 2015, from http://formulas.tutorvista.com/physics/projectile-motion-formula.html

Fitzpatrick, R. (2015). Projectile Motion with Air Resistance. Farside.ph.utexas.edu. Retrieved 16 April 2015, from http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node29.html

Lab Report - Boiling Point

LAB REPORT - BOILING POINT

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

Hypothesis - The more benzoic acid we have in our solution, the more molality our mixture will have; this means that when we have more molality and more mass the boiling point of the solution is higher. We can prove our opinion with the next formulas:

Results

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
0.5	0,82	58,8	58,0	58,4	2,19
1.0	1,64	60,7	60,5	60,6	4,38
1.5	2,46	51,5*	51,3*	51,4*	6,57
2.0	3,28	65,3	64,7	65,0	8,76
2.5	4,10	67,1	67,1	67,1	10,95

*Here, we can see an anomaly in the data, and it does not match the pattern of the data obtained.

GRAPH:

Conclusion - As we thought, the boiling point of our solutions increases as there is more molality and more mass this happens because the relationship between the ebullioscopic constant and the molality. When we calculate the variation of the boiling point if we have more amount of the mass the change in the boiling point will be higher (higher boiling point).

Evaluation - Apparently the method of this experiment is quite good however it was difficult to measure the 5 grams of acetone accurately as the way to measure the acetone in our opinion was not the best one, so to solve this is easy, instead of us measuring the 5 grams it could already be measured.

Also we found a problem to dissolve well the benzoic acid especially when we had to dissolve higher quantities such as 2.0 grams and 2.5 grams of the acid in only 5 grams of acetone, so the solution to this would be that the quantities of the acid are a bit lower.

As the water bath was quite hot we found difficult to get the test tube out and this probably affected the results, so if we had to do it again we would improve this and the method could put to use a test tube holder to take them out with less or no problem.

As always there are human errors, for example, not dissolving the benzoic acid in the acetone which will then affect the temperature or mess up with the test tubes which will affect the results.

We have not used any references for this lab report, except from our notes or the weebly to check formulas.

ScienceSFP,. (2015). Colligative Properties. Sciencesfp.com. Retrieved 5 March 2015, from http://www.sciencesfp.com/unit-3---colligative-properties.html

Lab Report - Viscosity

Background Information

The physical property that we had to investigate was viscosity. Viscosity is the quantity which describes a liquid’s resistance to flow. “Fluids resist the relative motion of immersed objects through them as well as to the motion of layers with differing velocities within them.” (Elert, 2015)

When the Intermolecular Forces of the substance are strong, the rate of viscosity is larger; and as weak as the IMF’s are, the lower the viscosity of the liquid is. The opposite of viscosity is fluidity, so when the viscosity is low, the liquid is fluid, while if the viscosity is high, the liquid is viscous.

Viscosity is affected by temperature; when we heat the liquid, its viscosity will decrease easily, whereas if we cool it down, its viscosity will increase. This happens because when we increase the temperature, we are giving molecules energy, so the average speed of the molecules increases. This results in the molecules being less time stuck to each other. In conclusion, when we rise temperature, intermolecular forces decrease and molecules interact without being pulled down by each other. On the other hand, when we freeze or cool down the liquid, we are taking away energy from the molecules, so they will move slower and will make contact for longer, increasing the viscosity. (Wen, n.d.)

Acetate

An acetate is an anion (negative ion) which is commonly found in aqueous solutions. It’s chemical formula is: C2H3O2. If the acetate ion is present in solution, then there must also be a cation together forming a soluble salt. A small fraction of the acetate ions will react with water, to make CH3COOH and hydroxide ion.

It is usual to find neutral molecules formed by the combination of an acetate ion and a positive ion (cation), the most common one is hydrogen acetate.

Hypothesis

The stronger the Intermolecular Forces of the chemical are, the more viscosity the liquid will have. This happens because the bonds made between the elements are stronger, so they create a stronger structure, which stops the ball from falling down easily.

Data

Table 1:

	Time the ball takes to reach the bottom of the tube (seconds)
	Propyl Acetate	Methyl Acetate	Ethyl Acetate	Butyl Acetate
TRY 1	1,25	1,34	0,57	0,48
TRY 2	0,79	0,84	0,57	0,38
TRY 3	0,53	0,34	0,47	0,40
TRY 4	0, 85	0,60	0,53	0,69
TRY 5	0,79	0,69	0,60	0,62
Average	0,79	0,69	0,57	0,48

Conclusion

The chemical in which the ball took more time to reach the end of the tube was Propyl Acetate, with an average time of 0,79 seconds, so it looks like it has a stronger intermolecular forces, which is hydrogen bonding.

On the other hand, the chemical in which the ball took less time to reach the end of the tube was Butyl Acetate, with an average time of 0,48 seconds, so it looks like it has a weaker intermolecular forces.

Evaluation

The principal error of this experiment probably has been that the plasticine ball went down through the test tube really fast, so we did not stop the stopwatch in time, which results   so instead of using plasticine it could be use a material that took more time to go down through the test tube, use a bigger test tube or even for the timing use a computer program to measure the time electronically.  In addition to this we probably didn't drop the ball from the same height all the time, so to solve this we could be conscious about it or establish a certain height (for example 8 cm) to drop the ball every time.

When taking the time was quite imprecise as it took less than a second, so it was very difficult to stop the stopwatch at the exact time it has reached the bottom of the test tube.

As human errors the principal one could be if they are not well labeled to mess up with the acetates and think that one type is another.

Step 5 (return the liquid of the measuring cylinder into its container and retrieve the balls) could be a problem if you didn´t remember in which test tube was each acetate, so probably the best way to solve this could be to do the experiment first with for example propyl acetate, then with methyl, ethyl and butyl .

Bibliography

Elert, G. (2015). Viscosity - The Physics Hypertextbook. Physics.info. Retrieved 21 January 2015, from http://physics.info/viscosity/

Wen, C. Viscosity - Chemwiki. Chemwiki.ucdavis.edu. Retrieved 21 January 2015, from http://chemwiki.ucdavis.edu/Physical_Chemistry/Physical_Properties_of_Matter/Bulk_Properties/Viscosity

Royal Society of Chemistry,. Acetate | C2H3O2 | ChemSpider. Chemspider.com. Retrieved 23 January 2015, from http://www.chemspider.com/Chemical-Structure.170.html