It's good you maintained the interest.

I see I made a silly mistake as well.

I thought F was given in kN but it is just in N so my figures are 1000 times too large.

Anyway the fourth fource.

This acts at the point of contact between the hammer head and the table.

That is the point of action of V on the hammer head.

It is of course the horizontal force of friction.

This shows that the claw hammer nail extractor

**will not work without friction.**
Without friction the hammer head would slide along the table.

This friction force acts through the point about which I have taken moments so has zero moments about this point.

So the moment equilibrium is correct.

In order to find the friction required you add this into the equation for horizontal equilibrium

So R sin(theta) = F + Friction

(The frition stops the hammer head skidding to the left away from F and so acts in the same direction as F)

1039/2 = 150 + friction

Friction = 520 - 150 = 370 N