Determine the angle of an incline that would yield a constant velocity, given the coefficient of kinetic friction is 0.10.

Respuesta :

Answer:

[tex]\theta=5.71^{o}[/tex]

Explanation:

In order to solve this problem, we mus start by drawing a free body diagram of the given situation (See attached picture).

From the free body diagram we can now do a sum of forces in the x and y direction. Let's start with the y-direction:

[tex]\sum F_{y}=0[/tex]

[tex]-W_{y}+N=0[/tex]

[tex]N=W_{y}[/tex]

so:

[tex]N=mgcos(\theta)[/tex]

now we can go ahead and do a sum of forces in the x-direction:

[tex]\sum F_{x}=0[/tex]

the sum of forces in x is 0 because it's moving at a constant speed.

[tex]-f+W_{x}=0[/tex]

[tex]-\mu_{k}N+mg sen(\theta)=0[/tex]

[tex]-\mu_{k}mg cos(\theta)+mg sen(\theta)=0[/tex]

so now we solve for theta. We can start by factoring mg so we get:

[tex]mg(-\mu_{k} cos(\theta)+sen(\theta))=0[/tex]

we can divide both sides into mg so we get:

[tex]-\mu_{k} cos(\theta)+sen(\theta)=0[/tex]

this tells us that the problem is independent of the mass of the object.

[tex]\mu_{k} cos(\theta)=sen(\theta)[/tex]

we now divide both sides of the equation into [tex]cos(\theta)[/tex] so we get:

[tex]\mu_{k}=\frac{sen(\theta)}{cos(\theta)}[/tex]

[tex]\mu_{k}=tan(\theta)[/tex]

so we now take the inverse function of tan to get:

[tex]\theta=tan^{-1}(\mu_{k})[/tex]

so now we can find our angle:

[tex]\theta=tan^{-1}(0.10)[/tex]

so

[tex]\theta=5.71^{o}[/tex]

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