Conservation of Momentum and Kinetic Energy

In summary, the conversation discusses the conservation of kinetic energy in a glider hitting a rubber band bumper. The data shows a 5% change in momentum and a 10%-15% change in kinetic energy, leading the speaker to conclude that momentum is conserved but kinetic energy is not. The speaker also presents calculations showing a decrease in kinetic energy with increasing velocity. The conversation ends with a question about whether the situation is perfectly elastic.
  • #1
Blangett
5
0

Homework Statement



I was wondering if a glider hits a rubber band bumper is kinetic energy conserved? I can't tell if the data I have supports conservation or loss. I am writing a lab report and data shows that momentum had around a 5% change. Kinetic energy had a 10%-15% change. Momentum is always conserved in a collision so I can conclude its conservered in this case. What is worrying me is that my data is wrong because momentum had a 5% change, I am not sure at what percentage makes it not conserved. I think Kinetic energy is not conserved in this case. Am I right?

Mass ~ 0.1833

Velocity Before
v1=0.4109
v2=0.4327
v3=0.5959


Velocity After
v1= 0.3898
v2= 0.4083
v3= 0.5462




Homework Equations



K= 1/2*m*v2

p= m*v

Percentage of change 1 - (kinetic before/kinetic after)

percentage of change momentum 1 - (momentum before/momentum after)



The Attempt at a Solution




(.013925671/0.015474070) = .89999 so 90% is conservered a 10% change

(0.01527887/0.017159564) = .890 so 89% is conserved a 11% change

(0.027342351/0.032544623) = .840 so 86% is conserved a 14% change

It seemed that the larger the velocity the more kinetic energy is lost. I am worried my conclusion is completely inaccurate.
 
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  • #2
Do you think your situation is perfectly elastic?
 
  • #3
I suppose its supposed to be since its a frictionless surface.
 

What is the conservation of momentum?

The conservation of momentum is a fundamental principle in physics that states that the total momentum of a closed system remains constant over time, regardless of any external forces acting on the system. This means that in a closed system, the total momentum before an event must be equal to the total momentum after the event.

What is the conservation of kinetic energy?

The conservation of kinetic energy is another fundamental principle in physics that states that the total kinetic energy of a closed system remains constant over time, regardless of any external forces acting on the system. This means that in a closed system, the total kinetic energy before an event must be equal to the total kinetic energy after the event.

What is the relationship between conservation of momentum and conservation of kinetic energy?

The conservation of momentum and conservation of kinetic energy are closely related principles. In fact, the conservation of momentum can be derived from the conservation of kinetic energy, as momentum is defined as the product of mass and velocity, while kinetic energy is defined as the product of half the mass and the square of the velocity.

Why is the conservation of momentum and kinetic energy important?

The conservation of momentum and kinetic energy are important principles in physics because they help us understand and predict the behavior of objects in motion. These principles are used in various fields, such as engineering, mechanics, and astrophysics, to analyze and design systems and objects.

Are there any exceptions to the conservation of momentum and kinetic energy?

The conservation of momentum and kinetic energy are valid principles in most situations, but there are some exceptions. These principles may not hold true in certain extreme conditions, such as when dealing with very small particles or at very high speeds. Additionally, in some cases where external forces are present, the conservation of momentum and kinetic energy may only apply to certain components of the system.

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