Force tension, friction, and coefficient of friction

Click For Summary

Homework Help Overview

The problem involves a scenario where a child pulls a friend on a sled with a constant tension in the rope, while considering the effects of friction. The subject area includes dynamics, specifically the forces acting on an object in motion and the role of friction in that context.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the forces acting on the sled and question the meaning of specific equations, such as Fw/2 = FT. There is an exploration of the net force on the sled and friend, as well as the implications of the frictional force being equal to the tension in the rope.

Discussion Status

The discussion is ongoing with participants raising questions about the assumptions made in the problem, such as the direction of the pull and the interpretation of the equations provided. Some participants express uncertainty about the completeness of the problem statement and whether it is sourced from a textbook.

Contextual Notes

There are indications that key information may be missing from the problem, leading to confusion about the setup and the equations involved. Participants are also questioning whether the sled is assumed to start from rest.

katie beisel
Messages
22
Reaction score
0

Homework Statement


A child pulls a friend on a sled. The child maintains a constant tension of 29.4 N in the rope. The combined mass of the friend and sled is 30.0 kg, and the coefficient of sliding friction between the sled and snow is 0.1. How far can the child pull her friend in 6 sec?

Homework Equations


F = ma
fk = muk x FN
Ff = mu x FN
Fw/2 = FT

The Attempt at a Solution


so I got the force weight of the child and the sled is 294 N
so the force normal of the child and sled is 294N
fk = 0.1 x 294 = 29.4
and the force tension is 29.4 so 29.4 = Fw/2
= 58.8 N = Fw but i don't know what weight that is
and i need another equation to put this in but i don't know which one
 
Physics news on Phys.org
Can we assume that the rope is being pulled horizontally?
katie beisel said:
Fw/2 = FT
I don't recognize that equation. Can you explain what it means?

katie beisel said:
so I got the force weight of the child and the sled is 294 N
so the force normal of the child and sled is 294N
fk = 0.1 x 294 = 29.4

Good. That's the force of friction.

So what's the net force on the sled+friend?

(I think there is key information missing from this problem statement. Is it from a textbook?)
 
  • Like
Likes   Reactions: katie beisel
Doc Al said:
(I think there is key information missing from this problem statement. Is it from a textbook?)
Probably can assume it means from rest.
 
What does Fw/2=Ft mean?
I believe you need to work out the resultant force on the sled. After finding the resultant force, use Newton Second law of motion, F=ma to find the acceleration,a
After that, you can apply formula for motion in constant acceleration. since u are assuming the sled is at rest, use the information that u have and substitute it to a suitable formula(there are 4 formulae for motion in constant acceleration) a,u,t and you can find the displacement
 
Doc Al said:
Can we assume that the rope is being pulled horizontally?

I don't recognize that equation. Can you explain what it means?
Good. That's the force of friction.

So what's the net force on the sled+friend?

(I think there is key information missing from this problem statement. Is it from a textbook?)
I'm actually not sure what the equation is, my teach wrote it on the board and i wrote it down, maybe it was just for a specific problem, I'm not sure.
well on the sled and friend there's the 29.4 N of friction pulling it back then the 29.4 N of FT, but wouldn't those cancel each other out? or is there something else?
 
katie beisel said:
well on the sled and friend there's the 29.4 N of friction pulling it back then the 29.4 N of FT, but wouldn't those cancel each other out?
Yes, they would give a net force of zero and thus no acceleration. So the problem seems to be a bit off. Is this a textbook problem? Or something your instructor made up?
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
1K
Replies
18
Views
3K
  • · Replies 20 ·
Replies
20
Views
3K
Replies
21
Views
3K
  • · Replies 10 ·
Replies
10
Views
4K
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K