[SEC 3] CHAPTER 5 - turning effects of forces

Question 1

Define moment of a force

Answer 1

The moment of a force about a point or pivot is the product of the force and the perpendicular distance from the line of action of the force to point/pivot

Question 2

what is moment of a force also called?

Answer 2

torque

Question 3

what is the formula for moment of force?

Answer 3

F x perpendicular d

Question 4

Why is it better to use a long spanner, rather than a short one, to tighten a nut on a bolt?

Answer 4

the perpendicular distance from force to the pivot is longer, therefore the moment produced is also greater since moment = F x perpendicular d

Question 5

what are the conditions for equilibrium?

Answer 5

1. the resultant force on the body is zero (irrational equilibrium)
2. the resultant moment on the body is zero (rotational equilibrium)

Question 6

define principle of moments

Answer 6

when a body is equilibrium, the sum of clockwise moments about the balance point or pivot is equal to the sum of anticlockwise moments abot the same point

Question 7

what is the formula for principle of moments?

Answer 7

total anticlockwise moment = total clockwise moment