Calculating the force of friction on an object

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Homework Help Overview

The problem involves calculating the force of friction on a 40.0-kg object being pulled along a horizontal surface with a force of 200 N at an angle of 30° below the horizontal. The coefficient of static friction is provided as 0.40, and multiple answer choices are given for the force of friction.

Discussion Character

  • Mixed

Approaches and Questions Raised

  • Participants discuss the calculated force of friction, with one stating a result of 197 N and questioning the discrepancy with the answer sheet. Others suggest potential misunderstandings regarding the type of friction involved and the relevance of certain parameters.

Discussion Status

Some participants have expressed agreement on the calculated value of 197 N, while others assert that the correct answer is 173 N. There is an ongoing exploration of the problem's details, including the implications of the friction coefficient and the force applied.

Contextual Notes

Participants note potential confusion regarding the type of friction (static vs. dynamic) and the relevance of the given parameters in the context of the problem.

purplecows
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Homework Statement


A 40.0-kg object is being pulled along a horizontal surface by means of a rope that exerts a force of 200 N at an angle of 30° below the horizontal. The coefficient of static friction between the object and the surface is 0.40. The force of friction on the object is:
A) 197 N
B) 173 N
C) 392 N
D) 157 N

Homework Equations


µ_s = F_s/ F_n

The Attempt at a Solution


f37784cfe70a77271ef546fefc925dc8.png

So I got 197 N, which was A. However, the answer was B on the answer sheet. What have I done wrong?
 
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I think you mean 'coefficient of dynamic friction'.

Your drawing is hard to decipher.
 
hi purplecows! welcome to pf! :wink:
purplecows said:
So I got 197 N, which was A.

so do i :smile:

(are you ok on your other thread?)
 
The answer is B and it's correct.

There are a lot of red herrings in this problem! I fell for the "static friction" coefficient myself.

The force is already given, so things like friction coefficients and mass are irrelevant.
 
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