How to Calculate Muzzle Speed in an Inelastic Collision?

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Homework Help Overview

The problem involves calculating the muzzle speed of a bullet that becomes embedded in a block of wood after an inelastic collision. The scenario includes parameters such as the mass of the bullet, the mass of the block, the coefficient of kinetic friction, and the distance the block travels before coming to rest.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to identify alternative equations to conservation of momentum for solving the problem, expressing uncertainty about the applicability of conservation of energy due to the inelastic nature of the collision. Some participants suggest using kinematic equations and Newton's second law to find acceleration, while others propose splitting the problem into two phases: post-collision motion and the collision itself.

Discussion Status

The discussion is ongoing, with participants exploring different approaches and questioning the use of conservation of energy in this context. There is no explicit consensus on the best method, but various lines of reasoning are being examined.

Contextual Notes

Participants are navigating the constraints of inelastic collisions and the implications of kinetic friction on the motion of the block after the collision. The original poster expresses confusion about the appropriate equations to use given the problem's conditions.

AeroFunk
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A 16 g bullet strikes and becomes embedded in a 1.30 kg block of wood placed on a horizontal surface just in front of the gun. If the coefficient of kinetic friction between the block and the surface is 0.22, and the impact drives the block a distance of 8.5 m before it comes to rest, what was the muzzle speed of the bullet?

Is there anthor equation i can use besides the conservation of momentum
mv=(m+M)v' I can't use conservation of energy because its inelastic right? So what can I do help please.
 
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Kinematic:

[tex]v^2 = v_{o}^2 + 2a \Delta x[/tex]

and Newton's 2nd Law to get the acceleration

[tex]\sum_{i=1}^{n} \vec{F}_{i} = m \vec{a}[/tex]
 
AeroFunk said:
I can't use conservation of energy because its inelastic right? So what can I do help please.
You can't use conservation of kinetic energy.
Use can use conservation of energy.
 
AeroFunk said:
A 16 g bullet strikes and becomes embedded in a 1.30 kg block of wood placed on a horizontal surface just in front of the gun. If the coefficient of kinetic friction between the block and the surface is 0.22, and the impact drives the block a distance of 8.5 m before it comes to rest, what was the muzzle speed of the bullet?

Is there anthor equation i can use besides the conservation of momentum
mv=(m+M)v' I can't use conservation of energy because its inelastic right? So what can I do help please.
Split your problem in two:
1. Assume that after the collision is finished, the system begins moving with some velocity [tex]v_{0}[/tex]
Determine [tex]v_{0}[/tex] with Cyclovenom's first equation.
2. You may now use momentum conservation during the collision phase to determine the muzzle speed (assuming the bullet did not meet any air resistance in the phase between it is shot out until the collision begins)
 

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