Calculate the time of the impact of this force

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    Force Impact Time
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Homework Help Overview

The discussion revolves around calculating the time of impact of a force acting on a body with a mass of 5 kg, subjected to a force of 20 Newtons in the opposite direction of its movement, with an initial speed of 4 m/s. Participants are attempting to clarify the setup and calculations involved in this problem.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are questioning the initial and final velocities provided, as well as the sign of the force. There is an exploration of the calculations leading to a negative time result, prompting discussions on the correctness of the approach.

Discussion Status

Some participants are seeking clarification on the initial conditions and the calculations, noting that the time should be positive. There is mention of a reference book providing a different answer, which raises further questions about the problem statement and the method used to arrive at that answer.

Contextual Notes

Participants are discussing the need for the exact wording of the problem from the book to ensure accurate interpretation and calculation. There is an acknowledgment of potential discrepancies between the provided data and the expected results.

UNknown 2010
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Hi my question is :

Moving the body mass was affected in 5 KG force of 20 Newton in a counter direction to the direction of movement if the speed 4 m / s. Calculate the time of the impact of this force
is it right?

pi= mvi
= (5)(9)=40 kg.m|s
pf= mvf
= (5)(-4)=-20 kg.m|s
t = (pf - pi)|f
= (-20-45)|20 = -3.25 s
 
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Was the initial velocity + 9 m/s and the final velocity - 4 m/s? If so, then OK. (But the time will be positive.)
 


yeh (velocity + 9 m/s and the final velocity - 4 m/s)
but my answer is wrong because the time is not positive
can anybody help me ?!
 


UNknown 2010 said:
but my answer is wrong because the time is not positive
Done correctly, the time will be positive.

Note: The force is negative.
 


In the book the answer was 1.5 seconds. but how they answer it I don't know
 


UNknown 2010 said:
In the book the answer was 1.5 seconds. but how they answer it I don't know
Based on the data you provided, that answer seems incorrect. Can you post the problem exactly as given, word for word?

(What book is this from?)
 

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