Acceleration on a slant/coefficient of friction

AI Thread Summary
A block sliding up a 30-degree incline with an initial speed of 6.00 m/s and a coefficient of kinetic friction of 0.330 is analyzed to find how far it travels before stopping. The user initially misapplied the acceleration due to friction and gravity, calculating it as -11.3 m/s², but later corrected it to -2.80 m/s² using the appropriate frictional force equations. After deriving the time to reach maximum distance as 2.14 seconds, they calculated the distance traveled as 6.42 m, which did not match the expected answers. The discussion emphasizes the importance of correctly applying the coefficient of friction in conjunction with the incline's angle to determine the normal force. The user seeks confirmation on their method and results, indicating a need for further clarification on the concepts involved.
Crazdfanatic
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Homework Statement



A block is given an initial speed of 6.00 m/s as it slides up an inclined plane that makes an angle of 30 degrees with the horizontal. If the coefficient of kinetic friction is .330, how far up the incline will the block go?

Homework Equations



I messed around with the equation delta_x = v_initial + .5a*t^2 , not sure how the coefficient of friction works

The Attempt at a Solution



I tried setting a = - 11.3 m/s/s by using trig because of the slant on the horizon, then using the above distance formula to find the maximum distance it traveled. I tried multiplying the coefficient of friction into the acceleration part of the equation, but to no avail. Please help me figure out what I'm doing wrong. Maybe an explanation of coefficient of friction is all I really need, I don't know.
 
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The coefficient of friction defines the relation between the normal force (exerted perpendicular to the contact surface) and the frictional force (which is parallel to the surface).

Ffrict = u x Fnormal

On a ramp, the normal force is no longer equal to simply mg, which is where the angles come in. Give it another try using these principles.
 
Okay, so I looked at it again, and this is what I got.

I found the new acceleration by g(u)cos(30) . I ended up getting a = -2.80 m/s/s.

From there, I plugged it into the distance formula above, leaving me with:

delta_x = t(6.00) + .5(-2.80)t^2

I took the derivative with respect to t to find the t that would give me the max distance.
I got this.

0 = 6.00 + (-2.80)t
t = 2.14 s

I plug that back into the above equation to get delta_x.

I ended up getting delta_x = 6.42 m, which is nowhere near any of the answer choices.

Am I even on the right track?
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
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