Moments

Question 1

What must occur between two forces acting on an object for it to be in horizontal equilibrium?

Answer 1

1. resultant torque is zero

2. resultant force acting on the object is zero

Question 2

If 3 forces are acting on an object, when might the object be in equilibrium?

Answer 2

when the resultant force is zero. Therefore the vertical and horizontal components of the forces (resolved vectors) are equal AND opposite

Question 3

Define the moment of a force about a point

Answer 3

force × perpendicular (1) distance (from the point) (1)

Question 4

Explain what is meant by centre of gravity.

Answer 4

1 of:
the point in a body where the resultant torque is zero
[or where the (resultant) force of gravity acts or where the weight
acts through] (1)

Question 5

How can you tell the resultant force is constant by drawing a shape representing vectors?

Answer 5

1. closed triangle

2 so forces are in equilibrium

Question 6

Define the moment of a couple

Answer 6

Force x perpendicular distance between the lines of action of the forces

Question 7

What is a couple

Answer 7

A pair of equal and opposite forces action