turning effects of forces

Question 1

definition of a moment of force

Answer 1

the moment of a force is the product of the force and the perpendicular distance from the pivot to the line of action of force.

Question 2

formula of moment of force

Answer 2

F (in newtons)x D(in metres)

Question 3

si unit of moment

Answer 3

Nm

Question 4

what is clockwise moments

Answer 4

clockwise moments means that the direction of rotation caused by the force follows the direction of a clock’s hands.

Question 5

what is anticlockwise moments

Answer 5

anticlockwise moments means that the direction of the rotation caused by the force in the opposite direction to the movement of a clock’s hands.

Question 6

what is the principle of moments

Answer 6

the principle of moments states that when a body is in equilibrium, the sum of clockwise moments about the pivot is equal to the sum of anticlockwise moments about the same pivot.

Question 7

what are the conditions for a system to be in equilibrium

Answer 7

1. all forces in the system have to be balanced

2. the resultant moment about a pivot has to be 0

Question 8

why do we say “the sum” of moments

Answer 8

sometimes there might be more than 2 forces in a system.

Question 9

definition of centre of gravity

Answer 9

the centre of gravity i defined as the point through which its whole weight appears to act for any orientation of the object.