What Is the Critical Angle to Keep a Box Moving with Kinetic Friction?

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The discussion centers on determining the critical angle (theta) at which a box can no longer be pushed across a floor due to kinetic friction. The coefficient of kinetic friction is given as 0.41, and the pushing force is applied downward at an angle. A key point is that when theta exceeds a certain value, no amount of pushing force can move the box. The equation provided attempts to balance the forces but requires adjustments for large pushing forces, where the weight of the box can be neglected. Understanding the relationship between the angle, pushing force, and friction is crucial for solving the problem.
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while moving in, a new homeowner is pushing a box across the floor at constant velocity. the coefficient of kinetic friction between the box and the floor is 0.41. the pushing force is directed downward at an angle (theta) below the horizontal. when theta is greater than a certain value, it is not possible to move the box, no matter how large the pushing force is.

find that value of theta.


I tried this.

P= pushing force
x = theta
m = mass of box
g= 9.8 or accel of gravity

Pcosx = (Psinx +mg).41

no luck :(
 
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aftershock said:
P= pushing force
x = theta
m = mass of box
g= 9.8 or accel of gravity

Pcosx = (Psinx +mg).41

no luck :(

Well you're nearly there. If the pushing force is very large then Psinx >> mg and you can ignore
the weight of the box.
 

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