Momentum factor into the force applied to an object at rest

In summary, the conversation discusses the relationship between momentum and force in collisions. The initial momentum of a moving object determines its final speed and the force involved in the collision depends on the duration of the interaction. The example of breaking bones with weights shows that energy, not momentum, is involved in the breaking of objects. The equation F = dp/dt represents the relationship between force and momentum, but measuring the time of impact and the variability of force during the collision can make it difficult to apply.
  • #1
cscott
782
1
How does momentum factor into the force applied to an object at rest hit by another which is moving?
 
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  • #2
Assuming no external forces, momentum is conserved so the initial momentum of the moving object relates to that (as well as how elastic the collision is)- it determines the final speeds. However, the "force" involved in the collision will also depend upon how long the interaction takes. In order go from rest to whatever final speed the object has, it must accelerate during the collision. The longer the collision takes, the lower the acceleration and so the lower the force required.
 
  • #3
Lets say I have a human bone, and I'm putting weights on it until it snaps, then I have another bone but let the weights fall onto the bone. I'm assuming the second bone will break with less weight because we're letting the weights fall. It is momentum that's involved here? What equations would I be working with?
 
  • #4
cscott said:
Lets say I have a human bone, and I'm putting weights on it until it snaps, then I have another bone but let the weights fall onto the bone. I'm assuming the second bone will break with less weight because we're letting the weights fall. It is momentum that's involved here? What equations would I be working with?
No, its energy. There is an engineering test called a http://www2.umist.ac.uk/material/research/intmic/features/charpy/notes.htm that takes into account all the factors that Halls mentioned and calls the energy required to break a sample "impact toughness". By using a heavy pendulum to break a test sample, the energy required to break it can be measured simply by using the difference in the height of the pendulum between the upstroke and the downstroke and applying the potential energy equation.
 
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  • #5
The OP first question asked about the relationship between force and momentum, That relationship is:

F = dp/dt where Force equals the change in momentum divided by the change in
time (during the collision)

This relationship is not evident in the arm breaking scenario but is best seen with an example such as a tennis player serving a ball or a golfer tee-ing off. The tricky part is in measuring the time of impact. Also, the force may not be constant during the collision, hence the need for differential calculus.
 

1. What is momentum?

Momentum is a measure of the quantity of motion that an object has. It is calculated by multiplying an object's mass by its velocity.

2. How does momentum factor into the force applied to an object at rest?

According to Newton's Second Law of Motion, the force applied to an object is directly proportional to its mass and acceleration. Momentum is directly related to an object's mass and velocity, so it plays a crucial role in determining the force applied to an object at rest.

3. Can momentum be transferred between objects?

Yes, momentum can be transferred between objects through collisions or interactions. In a closed system, the total momentum remains constant, but it can be redistributed among the objects involved.

4. How does momentum affect the motion of an object?

Momentum affects the motion of an object by determining how much force is needed to change its velocity. The greater the momentum, the more force is required to change the object's motion.

5. What are some real-life examples of momentum in action?

Some examples of momentum in action include a car crash, where the momentum of the moving car causes damage to the stationary object, and a rocket launch, where the momentum of the rocket propels it into space. Sports such as football and hockey also involve momentum, as players use their momentum to gain speed and power in their movements.

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