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Help Physics Car Coast problem?
A car traveling at 23 m/s runs out of gas while traveling up a 9.0 ∘ slope.
How far will it coast before starting to roll back down?
If you could really dumb it down. I don't get the Sin Cos things or even how to put them in a calculator. PLEASE HELP I've tried everything!
4 Answers
- electron1Lv 75 years agoFavorite Answer
http://www.physicsclassroom.com/class/vectors/Less...
If you go to the website above, you will see a drawing of an object that is on an inclined plane. The following equation is used to determine the force that causes the object to accelerate as it slides down the inclined plane.
Force parallel = m * g ** sin θ
a = g * sin θ
In the problem that you have, the car is moving up the inclined plane. This means the force will cause the car to decelerate. You can use the following equation to determine the distance the car moves up the slope before starting to roll back down.
vf^2 = vi^2 + 2 * a * d, vf = 0, a = -9.8 * sin 9
0 = 23^2 + 2 * -9.8 * sin 9 * d
19.6 * sin 9 * d = 529
d = 529 ÷ (19.6 * sin 9)
This is approximately 172.5 meters. I hope my explanation and the drawing at the website help you understand how to solve this type of problem. If you still have some questions, you can contact me the following email address.
morrison60957@yahoo.com
- BrainardLv 75 years ago
Let x = vertical distance gained
h = distance up the plane
Then
x/h = sin(9)
x = hsin(9)
Using the conservation of energy
Kinetic energy at the foot of the plane is equal to the potential energy gained
KE = 1/2m v^2 and PE = mg(hsin(9))
Therefore
1/2mv^2 = mghsin(9)
1/2 v^2 = ghsin(9)
h = (1/2v^2)/gsin(9)
= (1/2*23^2)/9.8sin(9)
= 172.53 m
Does it deserve best answer?
- oldprofLv 75 years ago
If you don't get the sine cosine things, then why are you taking physics? Why does your school even allow such a thing? It's early in the term; transfer to another curriculum, one that does not require basic trig.