Ch - 4 (Moments, Equilibrium and Centre of Gravity)

Question 1

Define moment

Answer 1

The turning effect of a force about a pivot.

Question 2

Equation of Moment.

Answer 2

M = F x d

M = Moment (Nm)
F = Force (N)
d = perpendicular distance (m)

Question 3

What is the principle of moment.

Answer 3

If an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot.

Sum of clockwise moment = Sum on anticlockwise moment.

Question 4

What is equilibrium.

Answer 4

Equilibrium is when the object keeps doing what it’s doing, without any change.

Question 5

When will an object be in equilibrium.

Answer 5

• No resultant force
• No resultant moment

Question 6

Define centre of gravity

Answer 6

The point at which the weight of the object may be considered to act.

Question 7

How Do we know if an object is stable.

Answer 7

1. Wider base —> Low venter of gravity –> More stable
2. Smaller base —> High center of gravity –> Less stable

Question 8

What are easy ways to find centre of gravity.

Answer 8

1. For regular shapes:
   - The point at which lines of symmetry meet.
2. For irregular shapes:
   - The point at which there is more matter

Question 9

How do we know if an object is stable?

Answer 9

If the center of gravity point, when extended, passes through the base, then it will not topple over.