Moments 1.3

Question 1

What are the conditions for equilibrium? (2)

Answer 1

Fr = 0
£M = 0

Question 2

Equation for a moment

Answer 2

M = f x d (L)

Question 3

What is the principle of moments

Answer 3

For a system in a state of rotational equilibrium, the summation of the anti-clockwise moments about a point equals the summation of the clockwise moments about the same point.

Question 4

Definition of centre of gravity/mass

Answer 4

The point at which the entire weight/mass of an object seems to act

Question 5

How do you find forces at a pivot if there are 2 pivots

Answer 5

Let one of the forces = 0 and take moments about that point

Question 6

How do you find the resultant force if it is a diagonal (tension, right angled triangle)

Answer 6

Resolve the diagonal force into vertical and horizontal components , use Pythagoras and/or sohcahtoa to find hypotenuse (diagonal force) don’t forget to label with an arrow and symbol

Question 7

4 conditions required for a couple

Answer 7

Forces are…
In opposite directions
Not along the same straight line
Same size
Parallel