Help with Physics 11 Kinematics.

AI Thread Summary
A 5.0kg concrete block accelerates down a 34° slope at 4.2m/s², and the goal is to find the coefficient of friction. The discussion highlights the importance of using the correct angle, as the problem specifies 34° instead of 30°. Participants emphasize the need for a free body diagram and accurate calculations of forces, including gravitational components. The friction force is linked to the normal force, and it's crucial to incorporate the block's acceleration into the equations. Accurate unit usage and correct angle application are essential for solving the problem effectively.
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Homework Statement



A 5.0kg concrete block accelerates down a 34° slope at 4.2m/s^2. Find the coefficient of friction between the block and the slope.


Homework Equations



Fg=5*9.8=45

x=45sin30

y=45cos30


The Attempt at a Solution



a=(mgsinθ-Ff)/m → Ff=mgsinθ-ma

Thanks
 
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Welcome to PF,
Have you drawn your free body diagram? How did you get your x and y components? The question states that the slope is at a 34° angle to the horizontal, not 30°.

Hint: Friction force = μN

Hint 2: Remember to add units to EVERYTHING.
 
Yes, I have drawn a FBD with x and y components that is perpendicular to the ramp.

I used the Fg to find the x by going Fgsin30°. Which would be the same as Fn.

Where would I go from this step?
 
aznpiggy said:
I used the Fg to find the x by going Fgsin30°. Which would be the same as Fn.

Why are you using 30° as your angle when it states in the question that it is 34°?

Your x component isn't the same as your y component, which would be the normal force (Fn). You must also consider the acceleration of the concrete block in your calculations.
 
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