Turning Effect of Forces

Why does F1 have a smaller magnitude than F2 but the same moment.

The perpendicular distance from the pivot to the line of action of F1 is larger than the perpendicular distance of the pivot to the line of action of F2. A smaller F1 is needed to produce an anticlockwise moment that balances the clockwise moment of F2.

Explain in terms of moments why the crane topples

There is an anti-clockwise moment of W about point P.

Why does a lower centre of gravity create more stability?

As the cg is lowered, a larger angle of tilt is needed for the line of action of the weight to no longer pass through the base.

C. The beam is in equilibrium so the moments are balanced. The distance from the line of action of both are the same so the weight is also the same.

What is the turning effect of a moment

The product of a force and the perpendicular from its line of action to the pivot.

What are the requirements for an ibject to be in equilibrium

The resultant force acting on it is zero and the resultant moment acting on it is zero

What is the centre of gravity

An imaginary point where the weight of the object seems to act.

What is the principle of moments

When a body is in equilibrium, the sum of clockwise moments about its pivot is the equal to the sum of anti-clockwise moments about the same pivot.

What is stability

The stability of an object is a measure of its ability to return to its original position

Why does the object move back into its original position?

The centre of gravity is above the base. There is a perpednciular distance between the pivot and the line of action of the weight, producing an anticlockwise moments that helps the object return to its original position