Find the magnitudes of all of the forces acting on the sled

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Homework Help Overview

The problem involves analyzing the forces acting on a sled being pulled by a rope at an angle, with the sled accelerating horizontally. The subject area includes dynamics and vector resolution of forces.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the components of the forces acting on the sled, including the normal force, gravitational force, and the tension in the rope. Questions arise regarding the correct method for summing these forces to find the net force.

Discussion Status

Some participants have provided guidance on the necessity of vector addition for the forces, indicating that the original poster's approach may need adjustment. There is an ongoing exploration of how to correctly sum the forces, with participants seeking clarification on the process.

Contextual Notes

The discussion highlights potential confusion regarding the addition of forces as vectors versus scalars, and the original poster expresses uncertainty about their calculations and whether they have overlooked any aspects of the problem.

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Homework Statement


A person pulls on a rope attached to a 5 kg sled. The rope makes an angle of 30 degrees with the horizontal. Sled accelerates horizontally at 1.7 m/s^2. There is no friction.

Homework Equations


ma = Fnet
mg = Fgravity

The Attempt at a Solution


Fnorm = Earth force up on sled
Fr = the force of the rope of the sled being pulled

The x and y components for Fr would be y = Frsinθ and x=Frcosθ.
Vector of Fnorm = <0, Fnorm>
Vector of Fg = <0, -50>
Vector of Fr = <Frcos30, Frsin30>

Fnetx => 8.5 = Frcos30
Fnety => 0 = Fc - 50 + Frsin30

So I got this far and starting doing algebraic stuff to solve for Fr and then plugging that into the second equation. From there, I solved for Fc, and the value was 45.095 N. And from the Fnetx equation, Fr = 9.8 N.
However, when I added all the magnitudes of forces, my answer does not equal to the Fnet, which is ma = 8.5 N.
Can someone help me with this? Have I forgotten something? Am I even doing this right?
 
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Show us how you added up the forces to get the net force. Your answers so far look OK.

Chet
 
For the net force, I did the force magnitude of Fnorm plus force magnitude of Fr minus the force magnitude of Fg, which is 8.5 N + 45.095 N - 50 N. That answer got me 3.595 N.
 
NkaujHelp said:
For the net force, I did the force magnitude of Fnorm plus force magnitude of Fr minus the force magnitude of Fg, which is 8.5 N + 45.095 N - 50 N. That answer got me 3.595 N.
The forces have to be added as vectors, not as scalars.

Chet
 
Chestermiller said:
The forces have to be added as vectors, not as scalars.

Chet

How do I do that?
 
NkaujHelp said:
How do I do that?
You do it by adding their components. But, you've already done that.

Chet
 

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