Chapter 5 (Turning effects of forces)

Question 1

What is the moment of a force

Answer 1

The product of the force F and the perpendicular distance d from the pivot to the line of action of the force

Question 2

How to calculate moment

Answer 2

M=Fd
F (force)
d (perpendicular distance from the pivot to the line of action of the force)
M (moment) (Nm)

Question 3

What is the principle of moments

Answer 3

When a body is in equilibrium, the sum of clockwise moments about a pivot is equal to the sum of anticlockwise moments about the same pivot

Question 4

What are the conditions for equilibrium

Answer 4

-The resultant moment on the body is zero
-The resultant force on the body is also zero

Question 5

What is the centre of gravity

Answer 5

The centre of gravity is an imaginary point where the entire weight of the object seems to act

Question 6

What is stability

Answer 6

stability is the measure of an objects ability to return to its original position

Question 7

How to find out if a object will
i) return to its original position
ii) balance on its edge
iii) topple over

Answer 7

i) When the vertical line of weight through its centre of gravity still falls within its base
ii) when the centre of gravity is in line with the pivot
iii) When the vertical line through its centre of gravity falls outside its base

Question 8

What affects stability of an object

Answer 8

-how low the centre of gravity of an object is
-how big or small the base area of an object is