Solve for Pulling Force for Sled w/ Mass, Angle, & Coeff. of Friction

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Homework Help Overview

The problem involves determining the minimum pulling force required to move a sled with a given mass at an angle, considering static friction. The context includes forces acting in both horizontal and vertical directions, as well as the implications of static conditions.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the implications of the problem being a statics scenario, questioning the conditions of net force and acceleration. There are attempts to break down the forces acting in both the x and y directions, with considerations of trigonometric components of the pulling force.

Discussion Status

Participants are actively engaging with the problem, exploring the relationships between forces and discussing the setup of equations. Some guidance has been offered regarding the directionality of forces and the need for a free body diagram. There is an indication of progress, with one participant expressing gratitude for assistance.

Contextual Notes

There is a focus on the static nature of the problem, with discussions around the assumptions of forces being balanced. The specific values of mass, angle, and coefficient of friction are noted, but no further details or resolutions are provided.

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Homework Statement



A father gives his daughter a ride on a sled by applying a force F at an angle θ = 26.0° with respect to the horizontal. If the coefficient of static friction is µs = 0.153, and the combined mass of sled and child is m = 24.0 kg
What is the minimum amount of force required to move the sled from rest by
pulling it

Homework Equations



F=ma

The Attempt at a Solution



I have tried multiple ways and i keep getting the wrong answer,
I think i should take the sum of all the forces in the x direction and of the y direction and somehow get the force i need but I am not exactly sure.

HELP PLEASE?
 
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The words "minimum amount of force" and "from rest" imply that this is a statics problem. In statics, what is the special condition on the net force? What does the word "static" imply about the value of the acceleration in f=ma?
Once you figure that out, you should have your net x force components (which requires trig) sum to this special value for the net force as well as you net y force components (which also requires trig).
EDIT: Also make sure you have your pulling force in the correct direction. Did you draw a free body diagram?
 


runningninja said:
The words "minimum amount of force" and "from rest" imply that this is a statics problem. In statics, what is the special condition on the net force? What does the word "static" imply about the value of the acceleration in f=ma?
Once you figure that out, you should have your net x force components (which requires trig) sum to this special value for the net force as well as you net y force components (which also requires trig).

So "static" would imply that the value of acceleration =0 ?right?

so i have in the x direction:
F(pull,x) + F(friction,x) +W(x) + n(x) = 0
but there is no W or F(gravity) in the x direction so that equals zero and same for n(x) (normal force) =0.
therefore i have:
F(pull,x) +f(friction,x)=0 right?

In the y direction:
F(pull,y) + F(friction,y) +W(y) + n(y) = 0
F(friction,y)=0
therefore i have:
F(pull,y) +W(y) + n(y) = 0 right?

then F(pull,x) = F(pull)cosθ
and F(pull,y) =F(pull)sinθ

I all that I've said is correct now, what would i do now? or is there other things that i am missing ?
 


Since the force is pulling, is your pulling force positive or negative? Is your weight positive or negative?
I see two equations and two unknowns (Fpull and normal). Pull out your algebra toolkit and solve it.
 


thanks for your help, i got the answer :P
 

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