Solving for Final Velocity Using Impulse Momentum Theorem - Homework Help"

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Homework Help Overview

The discussion revolves around applying the impulse momentum theorem to determine the final velocity of an object at a specific time, using integral calculus to analyze the forces acting on it.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the use of the impulse momentum theorem and the integration of force over time to find the final velocity. Questions arise about the correctness of the approach and the details of the calculations, particularly regarding the integration process and the interpretation of angles in radians versus degrees.

Discussion Status

Some participants have provided guidance on the integration process and the importance of ensuring the correct mode for angle measurements. There is ongoing exploration of the calculations, with differing results being noted, but no consensus has been reached on the final velocity values.

Contextual Notes

Participants mention specific time constraints and the need for clarity on the calculations leading to the final velocity. There is also a focus on ensuring that the mathematical setup aligns with the physical principles being applied.

mpittma1
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Homework Statement


https://scontent-a-sjc.xx.fbcdn.net/hphotos-prn2/t1.0-9/10167935_1403417599934459_6123061969742894932_n.jpg


Homework Equations





The Attempt at a Solution


I used ∫Fdt = m(vf-vo)

and came up with -.822 m/s for the final velocity...

I have been reworking this problem over and over and cannot come up with a different answer...

Am i wrong in using the impulse momentum theorem?
 
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mpittma1 said:

Homework Statement


https://scontent-a-sjc.xx.fbcdn.net/hphotos-prn2/t1.0-9/10167935_1403417599934459_6123061969742894932_n.jpg

Homework Equations



The Attempt at a Solution


I used ∫Fdt = m(vf-vo)

and came up with -.822 m/s for the final velocity...

I have been reworking this problem over and over and cannot come up with a different answer...

Am i wrong in using the impulse momentum theorem?
You haven't given any details regarding how you came up with -.822 m/s for the final velocity.

Why are you trying to find the final velocity anyway ?
 
mpittma1 said:

Homework Statement


https://scontent-a-sjc.xx.fbcdn.net/hphotos-prn2/t1.0-9/10167935_1403417599934459_6123061969742894932_n.jpg


Homework Equations





The Attempt at a Solution


I used ∫Fdt = m(vf-vo)

and came up with -.822 m/s for the final velocity...

I have been reworking this problem over and over and cannot come up with a different answer...

Am i wrong in using the impulse momentum theorem?
Your approach is correct. Can you show us how you integrated? What is the anti-derivative of sin(ωt)?

AM
 
Andrew Mason said:
Your approach is correct. Can you show us how you integrated? What is the anti-derivative of sin(ωt)?

AM

sorry, should have done that from the get go, here is what i did: this is for when t = .55 seconds btw

https://scontent-a-sjc.xx.fbcdn.net/hphotos-prn2/t1.0-9/10001366_1403433926599493_210320460460652531_n.jpg
 
Last edited:
SammyS said:
You haven't given any details regarding how you came up with -.822 m/s for the final velocity.

Why are you trying to find the final velocity anyway ?

Im not trying to find the final velocity but the velocity at time = .55 seconds
 
mpittma1 said:
sorry, should have done that from the get go, here is what i did: this is for when t = .55 seconds btw

https://scontent-a-sjc.xx.fbcdn.net/hphotos-prn2/t1.0-9/10001366_1403433926599493_210320460460652531_n.jpg
Your integral is correct. I can't tell from your answer how you got the 9e-5 value but it is not correct. The given answer is correct. Remember the argument for cos(ωt) is in radians, not degrees.

According to your equation:

vf = (1/m)∫Fdt + v0

If you work that out you will get the answer that is given.

AM
 
Last edited:
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Andrew Mason said:
Your integral is correct. I can't tell from your answer how you got the 9e-5 value but it is not correct. The given answer is correct.

According to your equation:

vf = (1/m)∫Fdt + v0

If you work that out you will get the answer that is given.

AM

Worked it out still got v(.55) = -.812 m/s

the answer is suppose to be v(.55) = -.451 m/s
 
mpittma1 said:
Worked it out still got v(.55) = -.812 m/s

the answer is suppose to be v(.55) = -.451 m/s

As AM said, ωt is in radians .

Your result looks like your calculator is in degree mode.
 
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SammyS said:
As AM said, ωt is in radians .

Your result looks like your calculator is in degree mode.

Hahaha thanks guys
 

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