Ch6 Forces In Equilibrium

Question 1

Moment=?

Answer 1

moment=force x perpendicular distance

Question 2

State the principle of moments

Answer 2

the sum of the clockwise moments is equal to the sum of the anticlockwise moments

Question 3

What is a couple?

Answer 3

A pair of equal and opposite forces acting on a body but not along the same line.

Question 4

Define centre of mass

Answer 4

The point at which no single force will have a turning effect.

Question 5

Define unstable equilibrium

Answer 5

The centre of mass is above the point of support. If displaced, the centre of mass is no longer above the point of support so the weight acts to turn object further from equilibrium

Question 6

Define stable equilibrium

Answer 6

The centre of mass is directly below the point of support. If displaced, the weight no longer passes through point of support so it is returned to equilibrium.

Question 7

What condition is necessary for a tilted object to topple?

Answer 7

The line of action of the weight passes through the pivot.

Question 8

What condition necessary for an object on a slope to topple?

Answer 8

If line of action of the force lies outside support point/ pivot