What is the mass of this object?

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Homework Help Overview

The discussion revolves around a physics problem involving the calculation of mass based on a net force and a change in velocity over time. The subject area includes dynamics and kinematics.

Discussion Character

  • Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the calculation of acceleration and the subsequent determination of mass using the formula derived from Newton's second law. There is a focus on verifying calculations and addressing discrepancies between personal results and the answer key.

Discussion Status

Some participants have provided feedback on calculations, suggesting that the original poster may have made an error in their arithmetic. There is an ongoing exploration of the correct mass value, with multiple participants indicating that the answer key may contain a typographical error.

Contextual Notes

There is a noted discrepancy between the calculated mass and the answer key, with participants questioning the validity of the provided answer. The discussion highlights the importance of careful calculation in physics problems.

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Homework Statement



A net force of 200N is applied to an object, causing its velocity to change from 30km/h to 20km/h in 2.3s.


Homework Equations



What is the object's acceleration? What is its mass?

The Attempt at a Solution



I got the correct answer for acceleration (-1.2m/s^2), but I'm having trouble with finding the mass.

I'm getting 199kg (m = 200N/1.2m/s^2), but the answer key says 170g. How is that correct?
 
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200/1.2 does not equal 199.

The answer should indeed be about 170kg.
Check your calculations again.
 
Thanks.

Apparently I can't use my calculator properly.

I guess 170g is probably a typo in the book.
 
they probably meant 170kg.
I got 167.8kg, which approximated to two significant figures gives indeed 170kg.
 

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