TITILE
Momentum and Collision
OBJECTIVES
To determine the change in momentum and kinetic energy during collision.
APPARATUS
Digital timer
2 photogates
Air track
2 gliders with 10cm screen
PROCEDURES
Figure 1
1. Gliders were weigh and arranged the apparatus as shown in Figure 1 2. Digital timer started and measuring parameters were set for the velocity measurement. 3. Glider B with 10 grams were loaded of slotted weights at BOTH SIDES of the glider to prevent it from tipping. (Increased to 20 and 30 grams for the next experiments) 4. The first photo gate was placed which connected to the Timer 1 jack to the left at 60 cm mark. Second gate was position that was connected to the Timer 2, to the right jack at the 170cm mark.
5. 10 cm screen was mount on the glider. 6. The air-track was adjusted until it is level. The glider was allowed to move through the two photo gates at a constant velocity in order to determine whether there is velocity gradient between the two photo gates. Readjust the air track if necessary. 7. All previously measurement was reset. 8. The first glider (Glider A) was position at the end of the air track attached with elastic trigger system. The second glider (Glider B) was position in the middle of the two photo gates. (100 cm mark as example) 9. Glider A was released and it was let to collide with glider B. The first photo gate, will measure the velocity of the glider A before the collision automatically. The second photo gate will first be measure the velocity of glider B after the collision. When the glider B passed the photo gates, the time measured was recorded and the counter was reset and starts again immediately to get the velocity of glider A after collision. The time measured was recorded. 10. The procedure above was repeated using different slotted masses.
DATA
Glider A Mass (kg)
0.2087
Glider B (10+10) g 0.2289
Glider A
Glider A
0.2087
Glider B (20+20) g 0.2489
0.2087
Glider B (30+30) g 0.2689
Time before collision (s)
0.2989
0.4735
0.5465
1.2518
0.4212
1.0113
Time after collision (s)
0.6213
0.4109
1.3113
0.6321
0.9486
0.5565
DATA ANALYSIS
Glider A Velocity before collision (m/s) Velocity after collision (m/s) Momentum before collision (kgm/s) Momentum after collision (kgm/s) Total momentum before collision (kgm/s) Total momentum after collision Kinetic energy before collision Kinetic energy after collision Total kinetic energy before collision Total kinetic energy after collision
Glider A
1.3391
Glider B (10+10)g 0.2289
Glider A
0.7319
Glider B (20+20)g 0.7988
0.9497
Glider B (30+30) g 0.9889
0.4829
0.7301
0.2288
0.4746
0.3163
0.5390
0.2795
0.4834
0.1527
0.1988
0.1982
0.2659
0.1008
0.1671
0.0478
0.1181
0.0660
0.1449
0.7629
0.3515
0.4041
0.2679
0.1659
0.2109
0.1398
0.2417
0.0764
0.0994
0.0991
0.1330
0.0504
0.0836
0.0239
0.0591
0.0330
0.0725
0.3815
0.1758
0.2321
0.1340
0.0830
0.1055
DISCUSSION
For this chapter, 3 experiment is carried out to determine the change in momentum and kinetic energy during collision. According to Newton ’s Second Law, the net force acting on a body is equal to the change of momentum experienced by the body. There are two types of collision. First, elastic collision. This is the type of collision in which both the momentum and kinetic energy of the system are conserved is called elastic collision. The collision between subatomic particles is generally elastic. The collision between two steel or glass balls is nearly elastic. In elastic collisions, the forces involving are conservative in nature. Another one is inelastic collision. This is the type of collision in which only momentum is conserved, not kinetic energy is called inelastic collision. Most of the collisions in daily life are inelastic in nature. The theory shows that in both type of collision, momentum is conserved but the kinetic energy is only conserved in elastic collision.
For first experiment, we used Glider A that weigh is 0.2087kg and Glider B is 0.2289kg. The Glider A distance before collision is 0.4m and 1.0m. After the collision, both of them is the same distance 0.3m. After that, we managed to record the time before and after collision using the digital timer. The time before collision for Gilder A and B are 0.2989s and 0.6213s. The time after collision are 0.4735s and 0.4109s. To get the velocity, we used the formula displacement divided by time. Using this formula, we get the velocity before collision for Glider A and B are 1.3391m/s and 2.1119m/s. The same formula was used to get the velocity after collision and for glider A and B are 0.4829m/s and 0.7301m/s. For the momentum we use formula mass time by velocity. And the results for Glider A and B before collision are 0.2795kgm/s and 0.4834kgm/s. And after collision are 0.1008kgm/s and 0.1671kgm/s. Next, for the total momentum, we used formula (mass time by velocity before-Glider A) plus (mass time by velocity before-Glider B). And the answers for this calculation is 0.7629kgm/s. For the total momentum after collision we used formula (mass time by velocity after-Glider A) plus (mass time by velocity after-Glider B). And the results was0.2679kgm/s. After that, we calculate the kinetic energy before collision. It was done using formula one over two multiply by mass and velocity. And the results were 0.1398J and 0.2417J. For the kinetic energy after collision, we used the same formula but with the glider after collision momentum. So, the results were 0.0504J and 0.0836J. Finally, we calculate the total kinetic energy before and after collision. We used formula (one over two multiply by mass and velocity) plus (one over two multiply by mass and velocity). For the before collision, we used velocity gliders before collision and the results was 0.3815J. And for the after collision, we used velocity glider after collision and the results was 0.1340J. At times the zeros to the right of the decimal point are omitted. However, these zeros must always be considered in calculations, as they indicate the accuracy of the volume measurement because they are significant figures.
In the next experiment, we used Glider A that weigh is 0.2087kg and Glider B is 0.2289kg. The Glider A distance before collision is 0.4m and 1.0m. After the collision, both of
them is the same distance 0.3m. After that, we managed to record the time before and afte r collision using the digital timer. The time before collision for Gilder A and B are 0.5465s and 1.2518s. The time after collision are 01.3113s and 0.6321s. To get the velocity, we used the formula displacement divided by time. Using this formula, we get the velocity before collision for Glider A and B are 0.7319m/s and 0.7988m/s. The same formula was used to get the velocity after collision and for glider A and B are 0.2288m/s and 0.4746m/s. For the momentum we use formula mass time by velocity. And the results for Glider A and B before collision are 0.1527kgm/s and 0.1988kgm/s. And after collision are 0.0478kgm/s and 0.1181kgm/s. Next, for the total momentum, we used formula (mass time by velocity beforeGlider A) plus (mass time by velocity before-Glider B). And the answers for this calculation is 0.3515kgm/s. For the total momentum after collision we used formula (mass time by velocity after-Glider A) plus (mass time by velocity after-Glider B). And the results were 0.1659kgm/s After that, we calculate the kinetic energy before collision. It was done using formula one over two multiply by mass and velocity. And the results were 0.0764J and 0.0994J. For the kinetic energy after collision, we used the same formula but with the glider after collision momentum. So, the results were 0.0239J and 0.0591J. Finally, we calculate the total kinetic energy before and after collision. We used formula (one over two multiply by mass and velocity) plus (one over two multiply by mass and velocity). For the before collision, we used velocity gliders before collision and the results was 0.1758J. And for the after collision, we used velocity glider after collision and the results was 0.0830J. This experiment we repeat the step for one more time to get much better accurate results. This is because we want to minimize any errors that can occurs. Although the final actual volume slightly different, the percentage is just 0.0097%. %. It’s can show that this experiment is really reliable and accurate. But, from the other perspective, if we look at the the time before collision for glider B and the time after collision for glider A were slightly higher than next experiment that we added more weigh onto it. . So, we can assume that maybe that was some human errors in conducting the procedure of this experiment. This error can be reduced by be more careful when doing experiment.
For the last experiment, we used Glider A that weigh is 0.2087kg and Glider B is 0.2689kg. The Glider A distance before collision is 0.4m and 1.0m. After the collision, both of them is the same distance 0.3m. After that, we managed to record the time before and after collision using the digital timer. The time before collision for Gilder A and B are 0.4212s and 1.0113s. The time after collision are 0.9486s and 0.5565s. To get the velocity, we used the formula displacement divided by time. Using this formula, we get the velocity before collision for Glider A and B are 0.9497m/s and 0.9889m/s. The same formula was used to get the velocity after collision and for glider A and B are 0.3163m/s and 0.5390m/s. For the momentum we use formula mass time by velocity. And the results for Glider A and B before collision are 0.1982kgm/s and 0.2659kgm/s. And after collision are 0.0660kgm/s and 0.1449kgm/s. Next, for the total momentum, we used formula (mass time by velocity beforeGlider A) plus (mass time by velocity before-Glider B). And the answers for this calculation is
0.4041kgm/s. For the total momentum after collision we used formula (mass time by velocity after-Glider A) plus (mass time by velocity after-Glider B).And the result was 0.2109kgm/s. After that, we calculate the kinetic energy before collision. It was done using formula one over two multiply by mass and velocity. And the results were 0.0991J and 0.1330J. For the kinetic energy after collision, we used the same formula but with the glider after collision momentum. So, the results were 0.0330J and 0.0725J. Finally, we calculate the total kinetic energy before and after collision. We used formula (one over two multiply by mass and velocity) plus (one over two multiply by mass and velocity). For the before collision, we used velocity gliders before collision and the results was 0.2321J. And for the after collision, we used velocity glider after collision and the results was 0.1055 J.
So, the results shows that the both quantities are different.To get a better result, we should repeat this experiment three times and make sure no small mistake is repeated such as the position of eye when we want to get reading of this experiment. We should position our eyes correctly to avoid small mistake that will affect our final result. In this experiment, there are some error when the time of from digital timer were taken. Its maybe because the gilder were moves so fast and we careless in put our effort to record the data accurately.
QUESTION
2. State the possible cause that give errors in this experiment.
The air flow from air conditioner that will make the gliders cannot achieve constant velocity. The gliders move so fast and did not have enough time to record it using digital timer.
3. Discuss how to overcome the errors state in 2.
Switch off the air conditioner and make sure that all the air flow such as wind had been blocked to prevent unnecessary force to the gliders that will give some error in this experiment. Record a video in front of the digital timer. So, we can play and pause or slowdown the playback to accurately take the right time on the spot.
CONCLUSION
From the experiment, it is shown that the momentum and kinetic energy does not conserved during elastic collision according to the results that shows the both quantities are completely different.
