Breaking Distance of a Car Traveling on an Inclined Plane

[Emma Hughes]

Homework Statement

Calculate the braking distance for a car traveling at a speed of 35.0m/s down a hill at an angle of 10.0 degrees relative to the horizontal.

Homework Equations

F=ma
^v=^u + 2as[/B]

The Attempt at a Solution

The teacher briefly explained this in class saying that the total force acting on the car when the braking force is applied (with direction of braking force as positive) is: ma - mgsin10, with a being the original acceleration of the car.

Although I don't understand how to get the original acceleration of the car or why it is used to get the braking force of the car.

 

[PeroK]

Homework Statement

Calculate the braking distance for a car traveling at a speed of 35.0m/s down a hill at an angle of 10.0 degrees relative to the horizontal.

Homework Equations

F=ma
^v=^u + 2as[/B]

The Attempt at a Solution

The teacher briefly explained this in class saying that the total force acting on the car when the braking force is applied (with direction of braking force as positive) is: ma - mgsin10, with a being the original acceleration of the car.

Although I don't understand how to get the original acceleration of the car or why it is used to get the braking force of the car.

I think that $a$ here is the deceleration of the car by braking on a horizontal road. Hence $ma$ is the braking force of the car.

On an incline you have gravity accelerating you, which is the second term in the equation.

Note that in this model it is assumed that the braking force of the car itself isn't affected by the angle. You might like to think about this and why in a more sophisticated model this may not be the case.

 

[scottdave]

I think that $a$ here is the deceleration of the car by braking on a horizontal road. Hence $ma$ is the braking force of the car.

On an incline you have gravity accelerating you, which is the second term in the equation.

Note that in this model it is assumed that the braking force of the car itself isn't affected by the angle. You might like to think about this and why in a more sophisticated model this may not be the case.

Whether the angle affect the braking force would depend on if the car is skidding (kinetic friction between tire and road) or the tires remain rolling (static friction between road and tire).
Reading the problem statement - the mass is not given, nor the "normal" acceleration.

So more information is needed to solve this.