3.2.3: Equilibrium

Question 1

Centre of gravity

Answer 1

An imaginary point where the entire weight of an object may be considered to act

Question 2

Equilibrium

Answer 2

A body is in equilibrium when the net force and net moment acting on it are zero

Question 2

Centre of mass

Answer 2

A force through which any externally applied force produces straight-line motion but no rotation

Question 3

Moment of a force

Answer 3

The product of a force and the perpendicular distance from the line of action of the force to the axis or point of rotation

Question 4

Couple

Answer 4

A pair of equal and parallel, but opposite forces acting at points separated by a distance, which only cause rotation

Question 5

Torque of a couple

Answer 5

The force multiplied by the perpendicular distance between the forces

Question 6

Principle of moments

Answer 6

For a body in rotational equilibrium, the sum of the clockwise moments about a point is equal to the sum of the anticlockwise moments about the same point