Analyzing Forces on a Car Attached to a Wall with a Rope

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Homework Help Overview

The problem involves analyzing the forces acting on a car that is attached to a wall via a rope, with a specific focus on the dynamics when the rope is at a 5-degree angle with the floor. The mass of the car is given as 2500 kg, and the scenario assumes no friction is present.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the separation of forces acting on the car and the rope, questioning the correct application of force equations in both x and y directions. There is uncertainty about the implications of the lack of friction and how it affects the force required to move the car.

Discussion Status

The discussion is ongoing, with participants raising questions about the assumptions made in the problem, particularly regarding the absence of friction. Some express confusion about the problem's intent and the implications of the forces involved, while others suggest that the problem may be poorly constructed.

Contextual Notes

Participants note the absence of friction in the scenario, which leads to questions about the feasibility of moving the car with minimal force. There is also mention of potential misinterpretations of the problem due to its presentation.

John_tawil
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Homework Statement


A rope is attached to a wall on one end and to a car on the other end. Someone pushes up on the rope and the car starts to move when the rope makes an angle of 5o with the floor. Mcar=2500kg
25z3sas.jpg

Homework Equations


ΣFx=ma
ΣFy=ma

The Attempt at a Solution


Look at the car and the rope separately.

I'm assuming the car has;
ΣFx=ma
ΣFy= 0
and the rope has the opposite;
ΣFx= 0
ΣFy= ma

But I'm not getting anywhere? Am I doing it right?
 
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You seems to be mixing up your x and y directions. (And so was i, because I was trying to read the printing laying on its side.:smile:)
The only force on the car that's accelerating it is horizontal. The trig will tell you what it is at 5o.
But I don't see how there would be any lower limit to the force needed if there is no friction.
 
John_tawil said:
But I'm not getting anywhere? Am I doing it right?
Nothing is accelerating here. (Not yet, anyway.)

Start by identifying the forces acting on the truck.
 
sophiecentaur said:
But I don't see how there would be any lower limit to the force needed if there is no friction.
Oops... I didn't notice that it said no friction. (Missed that when trying to read sideways.)

I don't get the point of the problem. With no friction, you need not be a muscleman to move the truck. A fly could do it.
 
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Doc Al said:
Oops... I didn't notice that it said no friction. (Missed that when trying to read sideways.)

I don't get the point of the problem. With no friction, you need not be a muscleman to move the truck. A fly could do it.
A touch of the "badly written questions' disease, I think.
 
So would you need 1N of force up to push to the left?
 
John_tawil said:
So would you need 1N of force up to push to the left?
If there's no friction, 1microNewton would produce finite acceleration. The question appears to be flawed - or it's angled to make you spot the nonsense aspect of it.
 
sophiecentaur said:
A touch of the "badly written questions' disease, I think.
Indeed. ?:)
 

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