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A box of uniform density with a square base of side length b and height 2b sits

ID: 1434148 • Letter: A

Question

A box of uniform density with a square base of side length b and height 2b sits on an incline. The coefficient of static friction between the box and the incline is mu_s. The angle of the incline theta is increased from theta until the box either tips over onto its side, or slides down the incline. For what relation between fi8 and 0 does the box slide? For what relation between mu_s and theta does the box tip? If mu_s = 0.55 does the box slide down the slope or tip? At what angle of the incline does it do this?

Explanation / Answer

a) For, box to slide

sN < mgsin

Also, N = mgcos

=> smgcos < mgsin

=> s < tan

For, box to tip

sN > mgsin

Also, N = mgcos

=> smgcos > mgsin

=> s > tan

where, = tan-1(b/2b)

b)    If s = 0.55

The box will tip

Because,   s = 0.55      and   tan = b/2b = 0.5

=>   s > tan

=> angle of inclination it occurs = tan-1( b/2b )

                                                     = tan-1(0.5)

                                                     = 26.56 degrees