Terminal Velocity Given Acceleration at Instantaneous Velocity

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Homework Help Overview

The discussion revolves around a physics problem related to terminal velocity, specifically addressing the relationship between acceleration and velocity under the influence of drag. The original poster presents a scenario where drag is proportional to velocity, with given values for velocity and acceleration.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to apply the equation of motion involving drag and gravitational force but questions the validity of their approach after arriving at a specific answer. Other participants inquire about the progress made and the points of confusion, emphasizing the need for more information before providing hints.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem and questioning the assumptions made, particularly regarding the mass of the object involved. Some guidance has been offered, but no consensus has been reached on the correct approach or solution.

Contextual Notes

There is a noted lack of information regarding the mass of the object, which is critical for solving the problem. Participants are also considering the implications of using velocity versus velocity squared in their calculations.

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Homework Statement


This is a repost of a homework like question. The previous thread I did not understand.
In the assumption that drag is proportional to velocity, and when v = 20 m/s, a = 7.35 m/s^2, find the terminal velocity.

Homework Equations


The thread stated that the equation most relevant would be ma = mg - kv.

The Attempt at a Solution


I substituted all know values to make m(7.35) = m(9.8) - k(20), and attempted to solve, but the answer is 40 m/s.
 
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How far did you get? Did you get stuck anywhere? It is too soon to give a hint, not enough has been done.
 
verty said:
How far did you get? Did you get stuck anywhere? It is too soon to give a hint, not enough has been done.
None of that information is needed. The initial question is that it is dropped from a large height. The only information given is the information proveded (v and a).
 
Never mind. I solved it by not replacing ma with 0 but by dividing by m first and replacing v with v^2.

In these types of problems, when is v or v^2 used?
 

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