Calculating Muzzle Velocity of a Spring-Powered Civil War Cannon

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Homework Help Overview

The discussion revolves around calculating the muzzle velocity of a spring-powered cannon designed to mimic Civil War artillery. The problem involves understanding the mechanics of spring compression, friction, and energy transfer in a physics context.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants are attempting to calculate the minimum force required to compress the spring and the resulting muzzle velocity. There are discussions about energy equations and the role of friction. Some participants express confusion regarding the variables involved in the energy equations.

Discussion Status

The discussion is active, with participants sharing calculations and questioning assumptions. Some have provided numerical values and equations, while others are seeking clarification on specific terms and concepts. There is no clear consensus yet on the interpretations or calculations presented.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information they can use or the methods they can apply. There is also a mention of needing to consider the angle of elevation, which adds complexity to the problem.

nitrostar
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As a hobby, you like to participate in reenactments of Civil War battles. Civil War cannons were muzzle loeaded, meaning that the gunpowder and the cannonball were inserted into the output end of the muzzle, then tamped into place with a long plunger. To recreate the authenticity of muzzle-loaded cannons, but without the danger of real cannons, Civil War buffs have invented a spring-powered cannon that fires a 1.0kg plastic ball. A spring, with constant 3000N/m, is mounted at the back of the barrel. You place a ball in the barrel, then use a long plunger to press the ball against the spring and lock the spring into place, ready for firing. In order for the latch to catch, the ball has to be moving at a speed of at least 2.0m/s when the spring has been compressed 30cm. The coefficient of friction of the ball in the barrel is 0.30. The plunger doens't touch the sides of the barrel.

a) if you push the plunger with a constant force, what is the minimum force that you must use to compress and latch the spring? You can assume that no effort was required to push the ball down the barrel to where it first contacts the spring.

b) what is the cannon's muzzle velocity if the ball travels a total distance of 1.5m to the end of the barrel?
 
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For a did this this
Fy=0=Fn-mg
Ffr=(mu)mg=2.94N
delta(K)=Wc+Wdiss+Wext
2J=-135J-0.882J+Wext
Wext=137.87J
W=Fd
F=459N
 
for b I'm a little bit confused I believe that:
delta(K)=Delta(U)+Wdiss
so velocity as soon as it leaves the spring is
vf=16.5m/s
 
I believe you need the angle of elevation of the cannon.
 
hmm... i think you just assume it is parallel to the ground
 
What is U and K in your equation?
 

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