Find mass of small block resting on the sloping side of a triangular block.

[angelcase]

A small block of mass m rests on the sloping side (45°) of a triangular block of mass M which itself rests on a horizontal table..
Assuming all surfaces are frictionless, determine the force P that must be applied to M so that m remains in a fixed position relative to M (that is, m doesn’t move on the incline).

Go to Example 1 to see the analysis of this system. Use the results of that analysis, together with your value for P (the units are N), to determine the weight (w) of the block, in N. (You need to know that the weight of M is 1.00 N.) Enter your value for w in the answer box below.

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Using the animation activity I found P (push force applied) to be equal to 2.34. In trying to determine w I am a little confused. W=mg, but I am not sure if this equation applies. In the example the following equation was derived: P=(M+m)g tan(theta)

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With the information given plugged in I got: 2.34=(1+m)g tan(45)...I wasn't sure if for g they want -9.8, since gravity is acting on all object.

 

[_coyote_]

So, I did 2.34=(1+m)(-9.8) tan(45). Then I solved for m and got -1.17. Finally, I plugged this into the equation w=mg and got 11.7 N.