Aim:
To find out whether momentum and kinetic energy are conserved.
Hypothesis:
Theoretically momentum should be conserved at all times whereas energy is lost if the collision is not a fully elastic one through heat and sound.
Variables:
The Independent variable is the initial and final mass of the trolley. The Dependent variable is the velocity of the trolley.
Procedure:
i) Set up apparatus as shown in the diagram.
ii) Start ticker timer and give the trolley a brisk push.
iii) Drop a book from your hands onto the trolley as it runs beneath.
iv) Run off enough tapes for each member of your group.
v) Measure the mass of your book and the trolley.
Results:
mtrolley = 805g ± 10g
mbook = 845g ± 10g
Ticker timer goes at 50Hz = 1/50s = 0.02s
vi = di / Δt vf = d2 / Δt
di = 5.4cm ± 0.1cm vi = 0.54ms-1
d2 = 1.8cm ± 0.1cm vf = 0.18ms-1
Ek = mv2 / 2
Ek before = 0.117369 J
Ek after = 0.02673 J
Pbefore = Pafter
Pbefore = mv Pbefore = 0.4347 kgms-1
Pafter = (m + m)v Pafter = 0.297 kgms-1
Evaluation and Analysis:
The obtained results don’t support my hypothesis since they show that neither energy nor momentum is conserved in this situation. The momentum after the collision decreased by a factor of approx. 1.5 whereas kinetic energy has decreased by almost a factor of 4.5. Due to friction from the table and the ticker timer the measurements taken were not 100% accurate. Friction was the main cause of inaccuracy in this experiment.
The Essay on Why We Must Conserve Energy ?
We are progressing in all spheres of life and this constant progress has been rather harmful on our natural resources. It is quite crucial to conserve energy. The conversation isn't only necessary to decrease a variety of kinds of pollution but also to save the resources for the future generation. As a result, we have to conserve energy for the much better future. How will need to we conserve ...
Kinetic energy is lost in this experiment and has been transformed into heat and sound.
Another factor contributing to inaccuracy is that the book was dropped by a person and humans tend to follow the trolley for a while before one drops the book onto the trolley. The book is also not always dropped from the same height making the collision have a larger impact on the trolley, if the book is dropped from a greater height then it affects the trolley more than if it were to be dropped from right above the trolley. Human error always contributes to inaccuracy and anomalies, any experiment done by humans will never be 100% accurate.
Conclusion:
This experiment has shown that momentum is not conserved in this type of collision. During the experiment one notices that the trolley tends to turn a bit to the left or the right making the trolley loose unnecessary velocity as it turns. To prevent that one could make a type of rail or enclosed track but that would increase the friction force acting on the trolley if the trolley were in contact with the sides of the track. Another factor which could have caused inaccurate values was that the ticker tape needed to pass through the narrow opening of the ticker timer applying even more friction on the trolley. The surface on which the trolley is on could have been made out of a less resistant material. The scale used to measure the trolley and the book was very inaccurate, a better scale could have provided better results.
