Calculating Ramp Angle for Box Sliding - Force & Motion

[dubversion11]

1. A box sits on a horizontal wooden ramp. The coefficient of static friction between the box and the ramp is 0.30. You grab one end of the ramp and lift it up, keeping the other end of the ramp on the ground. What is the angle between the ramp and the horizontal direction when the box begins to slide?



2. Fs=Us*Fn



3. I really don't know where to begin on this problem. I'm lost without a given mass of the box.

 

[tiny-tim]

Welcome to PF!

A box sits on a horizontal wooden ramp. The coefficient of static friction between the box and the ramp is 0.30. You grab one end of the ramp and lift it up, keeping the other end of the ramp on the ground. What is the angle between the ramp and the horizontal direction when the box begins to slide?
…
I really don't know where to begin on this problem. I'm lost without a given mass of the box.[/b]

Hi dubversion11! Welcome to PF!

Just call the mass "m", and do all the usual equations …

you'll find you can cancel the m's at the end!