Describing the second law of motion using linear momentum

In summary, the first law of motion is described using the equation F=ma and the second law is described using the equation F = dL/dt, which is based on linear momentum and can also be written as F = (d/dt)(mv). This equation accounts for the case where mass may vary with time.
  • #1
Trying2Learn
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Hi! This is a very simple question regarding terms of expressions.

  1. One law of motion is: F=ma
  2. Another, using L as the linear momentum, is: F = dL/dt

If the first equation can be characterized (ignoring reference frames) as a "coordinate-based equation" (since is concerned with the second derivative of the position coordinate) (also ignoring moving reference frames, etc.)...

Then, how would one characterizes the second equation? Yes, I can see it is different, but would one say "more general?"

How would one state the difference in the formulation? "?-based equation"
 
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  • #2
Trying2Learn said:
Summary:: Describing the second law of motion using linear momentum

Hi! This is a very simple question regarding terms of expressions.

  1. One law of motion is: F=ma
  2. Another, using L as the linear momentum, is: F = dL/dt

If the first equation can be characterized (ignoring reference frames) as a "coordinate-based equation" (since is concerned with the second derivative of the position coordinate) (also ignoring moving reference frames, etc.)...

Then, how would one characterizes the second equation? Yes, I can see it is different, but would one say "more general?"

How would one state the difference in the formulation? "?-based equation"

There is one important difference. ##F = ma## explicitly assumes a fixed mass. Whereas ##F = \frac{dL}{dt}## can be written as ##F = \frac{d}{dt}(mv)## and then you can have an argument about whether this includes the case where mass varies with time. I.e. whether you can write ##F = ma + \frac{dm}{dt}v## and what this means.
 
  • #3
Trying2Learn said:
... using L as the linear momentum...
..."?-based equation"
1) It doesn't matter how you call it
2) You say right there what it is based on
 
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1. What is the second law of motion?

The second law of motion, also known as Newton's second law, states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass. In other words, the greater the force applied to an object, the greater its acceleration will be, and the more mass an object has, the less it will accelerate.

2. How is the second law of motion related to linear momentum?

Linear momentum is a measure of an object's motion, and it is directly related to the second law of motion. According to the second law, the net force acting on an object will cause a change in its momentum. This means that the greater the force on an object, the greater its change in momentum will be.

3. What is the formula for calculating linear momentum?

The formula for calculating linear momentum is p = mv, where p is the momentum, m is the mass of the object, and v is its velocity. This formula shows that the momentum of an object is directly proportional to its mass and velocity.

4. How does the second law of motion explain the conservation of momentum?

The second law of motion explains the conservation of momentum by stating that in a closed system, the total momentum before an interaction will be equal to the total momentum after the interaction. This means that momentum is conserved, even if the individual momenta of the objects involved may change.

5. Can the second law of motion be applied to non-linear motion?

Yes, the second law of motion can be applied to non-linear motion. The law still holds true for objects moving in curved or circular paths, as long as the net force acting on the object is taken into account. In these cases, the change in momentum may result in changes in direction rather than just speed.

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