Conservation of momentum & inelastic collisions

In summary, the question is whether the principle of conservation of momentum is violated in the collision between a ball and the ground in an in-class experiment involving a motion sensor. The experiment consists of bouncing a ball and detecting its motion. The system in question may include both the ball and the ground, and momentum is always conserved in a closed system. The gravitational force between the Earth and the ball is not considered an external force in this system.
  • #1
chelseaalyssa
13
0

Homework Statement


This question is related to an in-class experiment. The lab involves bouncing a ball and using a motion sensor which creates a graph representing the motion.
The question is: Is the principle of conservation of momentum violated in this collision (the ball colliding with the ground)?


Homework Equations


m1v1i + m2v2i = m1v1i + m2v2i


The Attempt at a Solution


I don't think the collision violates the conservation of linear momentum law because the law applies to closed systems, and this system (when the ball collides with the earth) is not closed.
However I'm not sure if my theory on this is correct ...

Thanks in advance for your help :)
 
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  • #2
What does your system consist of? Is it just the ball? What have you learned about momentum conservation, namely when is momentum not conserved?
 
  • #3
The experiment only involves bouncing a ball on the ground (and detecting motion). Therefore, I am not sure if the system involves both the ball and the ground, or just the ball.
Regarding momentum, I know that momentum is always conserved in a closed system, but not a system which is affected by external forces.

thanks for helping :)
 
  • #4
In a collision there are always at least two parties that participate, an object cannot collide with itself. One party is the ball so it is reasonable to assume that the Earth (or floor which is attached to the Earth) is the other party. Is the Earth-ball a closed system? Are there external forces that affect it?
 
  • #5
Okay, so if the system is the earth-ball (and the collision between the two)... I'm not sure if the gravitational force from the Earth on the ball is included in the system, or is counted as an external force?
 
  • #6
It is not external to the Earth-ball system. The force that the Earth exerts on the ball is equal and opposite to the force that the ball exerts on the Earth. The Sun's force on the ball and Earth would be an external force, but we pretend that it is negligible.
 

1. What is conservation of momentum?

Conservation of momentum is a fundamental principle in physics that states that in a closed system, the total momentum of all objects before a collision is equal to the total momentum after the collision. This means that the total momentum of a system remains constant, regardless of any interactions or collisions within the system.

2. How is momentum calculated?

Momentum is calculated by multiplying an object's mass by its velocity. Mathematically, it can be expressed as p = m x v, where p is momentum, m is mass, and v is velocity. Momentum is typically measured in units of kilogram meters per second (kg·m/s).

3. What is an inelastic collision?

An inelastic collision is a type of collision in which kinetic energy is not conserved. In other words, the total kinetic energy of the system before the collision is not equal to the total kinetic energy after the collision. This can happen when some of the energy is converted into other forms, such as heat or sound, during the collision.

4. How does conservation of momentum apply to inelastic collisions?

Conservation of momentum still applies to inelastic collisions, even though kinetic energy is not conserved. This means that the total momentum of the system before the collision will still be equal to the total momentum after the collision. However, the final velocities of the objects involved may be different due to the loss of kinetic energy.

5. Can the conservation of momentum be violated?

No, the conservation of momentum is a fundamental law of physics and cannot be violated. In a closed system, momentum will always be conserved. However, in some situations, it may seem like momentum is not conserved due to external factors, such as friction or external forces. These factors should be taken into consideration when analyzing collisions to ensure that the conservation of momentum is upheld.

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