Unit conversion difficulties on simple problem

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Homework Help Overview

The problem involves calculating the work required to change the velocity of a particle from moving to the left at 27 m/s to moving to the right at 41 m/s. The particle's mass is given as 55 g, and the solution requires the answer in joules.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss unit conversion from grams to kilograms and the need to express the final answer in joules. There is confusion regarding the correct application of the work formula and the relationship between work, force, and velocity changes.

Discussion Status

Some participants are exploring the correct equations for work and kinetic energy, while others are questioning the initial calculations and assumptions. There is no clear consensus on the correct approach yet, but guidance has been offered regarding the need to consider kinetic energy changes.

Contextual Notes

Participants note the challenge of converting units appropriately and the potential misunderstanding of the work-energy relationship. There is an emphasis on the need for clarity regarding the definitions and equations related to work and energy.

xgoddess210
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Homework Statement



A 55 g particle is moving to the left at 27 m/s. How much work must be done on the particle to cause it to move to the right at 41 m/s? Answer in joules

Homework Equations





The Attempt at a Solution



27-(-41)=68 , 68*55= 3750

the units here are grams m/s. I need joules. I have no clue on how to make that happen. I can change the g to kg and even get it to Newtons (since I know a joule= Newton-meter) , but I can't take it any farther. Please help!
 
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xgoddess210 said:
27-(-41)=68 , 68*55= 3750

the units here are grams m/s. I need joules. I have no clue on how to make that happen. I can change the g to kg and even get it to Newtons (since I know a joule= Newton-meter) , but I can't take it any farther. Please help!

Just convert g to kg in your equation is all you need to do.
 
I tried that- It gives me an answer of 3.74, but that is wrong. This doesn't really make sense to me.
 
Once you have the correct units, your calculation is nonetheless in error. You have W = m\Delta v , which is the change in momentum, not the work done. What is the correct equation to use for Work?
 
oh! The equation I have for work is W=Fx, but all that is given to me is two velocities and a mass. Force is m*a so w=m*a*x. I guess I'm still at a loss here.
 
Oops. That's right. I just thought you were converting units wrong like your title was asking.

Overlooked that it was work and that's not work you have.

What about figuring the change in kinetic energy then?
 
Are you at all familiar with the Work-Energy equation or Conservation of Total Energy equations??
 

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