The work needed to move a mass of 5.41 kg 39.5 m

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Homework Help Overview

The problem involves calculating the work needed to move a mass of 5.41 kg a distance of 39.5 m against a resistive force of 24.9 N. The subject area pertains to mechanics, specifically the concepts of force and work.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the relationship between applied force, resistive force, and acceleration. There is an exploration of how to determine the minimum applied force required to overcome the resistive force. Questions arise regarding the notation used and the meaning of acceleration in the context of the problem.

Discussion Status

Participants are actively engaging with the problem, seeking clarification on the reasoning behind the calculations. Some guidance has been offered regarding the application of Newton's laws and the relationship between forces, but there is no explicit consensus on the approach to take.

Contextual Notes

There is a mention of the resistive force potentially being due to environmental factors, such as wind, which raises questions about the assumptions made in the problem setup. Participants express uncertainty about the acceleration and its role in determining the applied force.

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Homework Statement


The work needed to move a mass of 5.41 kg 39.5 m against a resistive force of 24.9 N is _____J.

Homework Equations


W = F x d

The Attempt at a Solution


F=ma
Fapplied - Resistive Force = 5.41(a)
 
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Welcome to PF;
F=ma
Fapplied - Resistive Force = 5.41(a)
... please explain your reasoning, and remember to include units in the answer.
I don't know what you mean by "(a)" in there. It looks like you are trying to calculate a force and you have noticed that you do not know the acceleration.

The work is the magnitude of the applied force multiplied by the distance moved in the direction of the applied force.

In the problem, you are told there is a "resistive" force - maybe that is the wind pushing on the object.
In order to move the object "against the wind", what is the minimum applied force that is needed?
 
Simon Bridge said:
Welcome to PF;
... please explain your reasoning, and remember to include units in the answer.
I don't know what you mean by "(a)" in there. It looks like you are trying to calculate a force and you have noticed that you do not know the acceleration.

The work is the magnitude of the applied force multiplied by the distance moved in the direction of the applied force.

In the problem, you are told there is a "resistive" force - maybe that is the wind pushing on the object.
In order to move the object "against the wind", what is the minimum applied force that is needed?

It's hard for me to explain due to the question only being worded like that in my homework assignment.
I meant 'a' as in acceleration. I am completely unaware of how to find the minimum applied force.
 
You use Newton's laws of motion ... ##\sum F = ma## will do it.

[edit: I am changing notation to better comply with PF rules...]
Say, ##F## is the magnitude of the applied force, and ##f## is the magnitude of the resistive force, and take the +x direction as positive ... then:

You already figured that ##F-f = ma## ... but you do not know the value of "a".
You know the object has to be moving in the direction of ##F## (which is against ##f##)... so what is the smallest value of ##F## that does this?
ie. If ##F = 1000f## ... which direction is the motion in? Is that the smallest ##F## can be?
 

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