Force Work on 5kg Particle Moving at Constant Velocity

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Discussion Overview

The discussion revolves around calculating the rate at which a force is doing work on a particle with a specified mass and velocity. The context includes homework-related problem-solving involving vector notation and the application of work and power concepts in physics.

Discussion Character

  • Homework-related, Mathematical reasoning

Main Points Raised

  • One participant presents a calculation involving the dot product of the force vector and the velocity vector to determine the work done by the force.
  • Another participant notes that power and work are scalar quantities, suggesting that the answer should not have a vector direction.
  • A subsequent reply proposes a value of -7 N*m/s, indicating a potential misunderstanding or correction regarding the sign of the power.
  • Another participant reiterates the -7 N*m/s value, questioning the implications of negative power.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the correct interpretation of the power calculation, with differing views on the sign of the result. No consensus is reached on the final answer.

Contextual Notes

There is a lack of clarity regarding the definitions of work and power in this context, as well as the implications of negative power. The discussion does not resolve the mathematical steps leading to the proposed values.

Nickluvn
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Homework Statement


A particle with mass 5kg travels with a constant velocity of 5 m xˆ − 2 m zˆ while ss
subject to a force of 1Nxˆ − 5Nyˆ + 6Nzˆ . At what rate is this force doing work on the particle?


Homework Equations


w = fd


The Attempt at a Solution


I changed it into vector notation

so it kinda looked like [5,0,-2][x^ y^ z^] dot product with [1 , -5 , 6] [ x^ y^ z^]

the answer i got was 5 N*m/s x^ - 12 N*m/s z^

this correct?
 
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Nickluvn said:

Homework Statement


A particle with mass 5kg travels with a constant velocity of 5 m xˆ − 2 m zˆ while ss
subject to a force of 1Nxˆ − 5Nyˆ + 6Nzˆ . At what rate is this force doing work on the particle?


Homework Equations


w = fd


The Attempt at a Solution


I changed it into vector notation

so it kinda looked like [5,0,-2][x^ y^ z^] dot product with [1 , -5 , 6] [ x^ y^ z^]

the answer i got was 5 N*m/s x^ - 12 N*m/s z^

this correct?
Almost. Power and work are scalar quantities. They have no vector direction. They are either positive or negative values.
 
So it would be -7 N*m/s?
 
Nickluvn said:
So it would be -7 N*m/s?
That's what I get... 0r -7 watts...hmmm, negative power ...
 

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