Help! I understand the problem, but I\'m having trouble putting that understandi

Question

Help!  I understand the problem, but I'm having trouble putting that understanding to use.  What should my drawing look like?  Please solve the rest as well.  All of the necessary information is in the above image.  Thanks!

A water wheel is symmetrically supported on two journal bearings (the simplest type - 20 rolling elements, just sliding contact). The millrace delivers 10 kg/s of water at a height of 2m above the downstream slide. Recall that the energy available from falling fluid is W = mgh The mill grinds flour, and the grindstone extracts 180 W of power from the shaft.

Explanation / Answer

The figure will look like: water is falling on the blades of the wheel so that

the kinetic energy of water which was converted from the potential energy will be used to rotate the wheel.

power available to rotate the wheel=m_dot*g*h=10*9.81*2=196.2 Watt

but only 180 watt power is extracted.

so power loss=196.2-180=16.2 watt

the power loss is due to friction

so P=16.2 watt ,w=1 rev/min=0.104 rad/s

we know P=w*T

T=16.2/0.104=155.77 Nm this is the torque exerted by the friction on shaft

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