Is Momentum Conserved in Our Collision Lab Experiment?

[soccergirl14]

So, here is my data:
TRIAL 1 TRIAL 2 TRIAL 3
MASS OF CAR 1 7.5 N 7.5 N 7.5 N
MASS OF CAR 2 7.5 N 7.5 N 7.5 N
TIME FOR CAR 1 (s) 8.63 8.31 9.40
TIME FOR CAR 2 (s) 7.50 10.72 8.78
DISPLACEMENT FOR CAR 1 (m) 305.00 365.00 348.60
DISPLACEMENT FOR CAR 2 (m) 387.50 369.10 305.10


And the questions from the lab are:
1. Find the velocity of each car after the collision. Remember it is
accelerating from rest.
2. Find the momentum for each car before and after the collision. Then find
the total momentum before the collision and the total momentum after
the collision. p1 + p2 = p1+ p2
3. Determine the % difference for the four different situations.

(The lab consisted of two cars placed side by side, when a button was pushed on one car a rod would extend and cause a collison, I hope that made sense!)



My issues:
-I kind of get the feeling from the first question that I may have used an incorrect approach in solving this, but I just divided the displacement by the time. (ex. 385.50m/7.50s=51.7m/s)
-Okay, for the second question, I would use p=mv to find the momentum. But wouldn't the momentum before the collision always be zero since it begins from rest? so wouldn't it end up looking like 0 = (whatever the added momentums after the collisons are)? meaning momentum is not conserved? I thought momentum was always conserved but maybe I am completely wrong.

 

[LowlyPion]

The cars move in opposite directions don't they?

 

[nlightner]

As a scientist, it is important to approach data analysis with a critical and objective mindset. There are a few issues that I can see with the data and questions provided in this lab.

Firstly, in order to accurately calculate the velocity of the cars after the collision, we need to know the initial and final positions of the cars. In this case, we only have the displacement, but not the starting point for each car. Without this information, it is not possible to accurately calculate the velocity.

Secondly, it seems that the masses of both cars are the same in all three trials. This may not accurately reflect a real-life scenario where the masses of the cars involved in a collision may be different. This could affect the results and make it difficult to draw any meaningful conclusions.

In regards to the second question, momentum is indeed conserved in a closed system. However, in this lab, we do not have enough information to determine if the system is closed. We do not know if there are any external forces acting on the cars during the collision, which could affect the momentum. Additionally, as mentioned before, without knowing the initial and final positions of the cars, it is not possible to accurately calculate the momentum.

Finally, the third question asks for the percentage difference for different situations, but it is not clear what these situations are. It is important to specify what is being compared and how the percentage difference is being calculated.

In conclusion, in order to accurately analyze and draw meaningful conclusions from the data, it is important to have all the necessary information and to clearly define the experimental setup and variables. Without this information, it is difficult to make any definitive statements about the conservation of momentum or the velocity of the cars after the collision.