Is Momentum Conserved in Our Collision Lab Experiment?

Click For Summary
SUMMARY

The discussion centers on the conservation of momentum in a collision lab experiment involving two cars, each with a mass of 7.5 N. Participants calculated velocities by dividing displacement by time, resulting in values such as 51.7 m/s for Car 1. The confusion arose regarding momentum calculations, particularly the misconception that total momentum before the collision is zero, despite both cars having initial velocities. The correct approach confirms that momentum is conserved, as the total momentum before and after the collision must equal each other.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Basic knowledge of kinematics, including velocity and displacement
  • Familiarity with momentum calculations using the formula p=mv
  • Concept of conservation of momentum in closed systems
NEXT STEPS
  • Review kinematic equations for calculating velocity and acceleration
  • Study the principle of conservation of momentum in elastic and inelastic collisions
  • Explore the impact of initial conditions on momentum calculations
  • Practice solving problems involving multiple objects in motion
USEFUL FOR

Students in physics courses, educators teaching mechanics, and anyone interested in understanding the principles of momentum and collision dynamics.

soccergirl14
Messages
11
Reaction score
0
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.
 
Physics news on Phys.org
The cars move in opposite directions don't they?
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
Replies
335
Views
17K
  • · Replies 16 ·
Replies
16
Views
4K
  • · Replies 15 ·
Replies
15
Views
4K
Replies
10
Views
3K
Replies
21
Views
3K
  • · Replies 12 ·
Replies
12
Views
1K
  • · Replies 11 ·
Replies
11
Views
3K