What height does the projectile reach when factoring in friction force?

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Homework Help Overview

The discussion revolves around a physics problem involving a popgun, where the original poster seeks to determine the height a projectile reaches after being fired, factoring in friction force. The problem is related to concepts of energy conservation and the spring force constant.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • The original poster attempts to understand how to incorporate friction force into the height calculation, questioning whether it should be subtracted from the energy equation. Other participants inquire about the specifics of the friction force, including its nature and location, and seek clarification on the complete problem context.

Discussion Status

Participants are actively engaging with the original poster's question, with some providing guidance on using conservation of energy principles. There is an exploration of different interpretations regarding the role of friction in the problem, but no consensus has been reached yet.

Contextual Notes

The problem is constrained by the need to relate it to a previous example, and the original poster expresses urgency in resolving the question by a deadline. The friction force is specified as a constant magnitude acting within the barrel of the popgun.

mtnbiker45
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Homework Statement


I have a homework question where it asks, "after the spring is compressed and the popgun fired, to what height does the projectile rise from point B? The question is related to an example problem in the book, where the example tells you to solve for "k", which is the spring force constant. By looking at the example i can find out what the equation for the height would be equal to, but i do not know where friction force comes into play. In the previous example it says, neglecting all resistive forces, determine the spring constant and in this example your determining height, but this time there is a resistive force (aka friction force). So, what do i do? Do i just minus the friction force.

equation for the height is

Yc= [MGYa+1/2KX^2]/MG where the lowercase letters are subscripts and Yc is the height that rises above point B.

So, my question is where does friction force go into this equation so that i find the height and so that I am not neglecting resistive forces(friction force)?LOOK AT OTHER POSTS FOR MORE IN DEPTH PLEASE HELP I NEED TO FIGURE THIS OUT BY TOMORROW
 
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Can you give the complete question? Where is the friction force: in the gun or in the air (as air resistance)? Is it a constant force?
 
ideasrule said:
Can you give the complete question? Where is the friction force: in the gun or in the air (as air resistance)? Is it a constant force?

it is hard to tell you the full problem because it relates to another problem but here is the full question from the book.

Consider the popgun in Example 8.3. Suppose the projectile mass, compression distance, and spring constant remain the same as given or calculated in the example. Suppose, however, there is a friction force of magnitude 2.00N acting on the projectile as it rubs against the interior of the barrel. The vertical length from point A to the end of the barrel is 0.600 m (a) After the spring is compressed and the popgun fired, to what height does th projectile rise above point B? (b) draw 4 energy bar charts for this situation, analogous to those in Figures 8.6c-d


spring constant from the example k=958N/m
 
so, sorry for not answering your question but the friction force is in the barrel of the gun
 
and if you're wondering where i got that height equation, the example provided in the book had k (spring force constant) equal to some letters and i just switched it around so that i got Yc= ...any help would be appreciated
 
i need to figure this one out by tomorrow, someone help please
 
mtnbiker45 said:
Consider the popgun in Example 8.3. Suppose the projectile mass, compression distance, and spring constant remain the same as given or calculated in the example. Suppose, however, there is a friction force of magnitude 2.00N acting on the projectile as it rubs against the interior of the barrel. The vertical length from point A to the end of the barrel is 0.600 m (a) After the spring is compressed and the popgun fired, to what height does th projectile rise above point B?

Try using the conservation of energy. The energy the popgun+bullet has at the start must equal the final energy of the popgun+bullet system, minus the energy lost by friction (which would just be W=Fd).
 

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