Forces acting on a car on an incline

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Homework Help Overview

The discussion revolves around the forces acting on a car parked on an incline, specifically focusing on the normal force and the car's potential acceleration in the absence of friction. The incline is described with a ratio of 1 in 30, and participants are exploring the implications of this setup on the forces involved.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the relationship between the normal force and gravitational forces acting on the car, questioning whether to assume F = N in the absence of friction. There are inquiries about distinguishing forces in different directions and the implications of releasing the handbrake.

Discussion Status

The discussion is active, with participants providing insights on the forces at play and questioning assumptions about friction and motion. Some guidance has been offered regarding the direction of forces and the expected movement of the car if the handbrake is released, but no consensus has been reached on the overall approach to the problem.

Contextual Notes

Participants are navigating the constraints of the problem, including the absence of friction and the specific incline ratio. There is an emphasis on clarifying the roles of different forces without providing a definitive solution.

TheBigDig
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Homework Statement
A 1100 kg car is parked on an incline of 1 in 30. What is the normal force acting on the car? In the absence of friction what would be the acceleration if the handbrake were released?
Relevant Equations
## \vec{F} = \mu_k \vec{N} ##
## F = mgsin\alpha ##
## N = mgcos\alpha ##
For part 1, I got ## tan \alpha = 1/30 ##
##\alpha = 1.9^{\circ}##
##mgcos(1.9) = 10774N##

I'm a little thrown off by the second part. Are we supposed to assume that in the absence of friction, F = N and then substitute F = ma to solve for this?
 
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TheBigDig said:
Homework Statement:: A 1100 kg car is parked on an incline of 1 in 30. What is the normal force acting on the car? In the absence of friction what would be the acceleration if the handbrake were released?
Relevant Equations:: ## \vec{F} = \mu_k \vec{N} ##
## F = mgsin\alpha ##
## F = mgcos\alpha ##

F = N
It would help if you were to distinguish forces in different directions instead of writing "F" in every case.
Which direction is the normal force? In which direction will the car move if the brake is released?
 
haruspex said:
It would help if you were to distinguish forces in different directions instead of writing "F" in every case.
Which direction is the normal force? In which direction will the car move if the brake is released?
Sorry yes of course. The normal force is perpendicular to the surface and the car will roll backward. I believe the model should correspond to this
main-qimg-1e095a892cea774cc9bbf38751a76228.png
 
The force acting parallel to the slope causes the car’s acceleration so, since F=ma, you have mgsin(θ)=ma so a=gsin(θ).
 
TheBigDig said:
Homework Statement:: A 1100 kg car is parked on an incline of 1 in 30. What is the normal force acting on the car? In the absence of friction what would be the acceleration if the handbrake were released?
If there is no friction, then whether the handbrake is on or not is irrelevant. The car will slide down the hill in any case.

If there is enough friction, then the handbrake will hold the car, but the car will roll down the hill if the handbrake is released.
 
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