(1.30P-1.33P) Moments

What is a moment?

The turning effect of a force about a pivot

State the relationship between moment of a force and its perpendicular distance from the pivot.

Moment = force * perpendicular distance from pivot

Where does the weight of a body act through? What about for an irregularly shaped object?

It acts through its center of gravity. If irregular, it lies vertically below its suspension point.

State the principle of moments.

In rotational equilibrium + a simple system of parallel forces acting in one plane,

sum of anti-clockwise moments = sum of clockwise moments.

How do upward forces on a beam supported at its ends vary with the position of a heavy object placed on the beam?

When moments are taken from the right hand side with the block further from it,

the force upward on the left support must be bigger to counteract it.

The opposite is true for the left hand side.