1. Prepared By: Shakil Raiman

2.  The turning effect of a force about a certain point is called moment (or torque)  The moment can be calculate using the following equation.  Moment = Force × Perpendicular distance of force from "pivot“  Moment of a force = F × d  Unit: Nm

3.  There are two types of moments 1. Clockwise moments 2. Anticlockwise moments

5.  Consider a person trying to open a door, by applying a force, of magnitude, F, as shown below.  The two obvious changes the person could make in order to open the door more easily are i)he/she could increase the distance "r“ ii)he/she could push at 90° to the door

6.  In equilibrium/balanced situation, Sum of Clockwise Moments = Sum of Anticlockwise Moments F 1 d 1 =F 2 d 2 +F 3 d 3

8.  The centre of gravity of a body is defined as the point through which its whole weight appears to act.  Centre of gravity and centre of mass is same if the object is in uniform gravitational field.  The centre of gravity of Regular Shaped Object is at the Geometrical Centre of the object.

9.  Centre of gravity of a regular shape is at its geometric centre.  For regular lamina, it is a point where it’s lines of symmetry meets.

10.  First make three holes at three different corners of the lamina.  Hang the lamina using one hole and put a plumb line. Mark the vertical line on the lamina.  Repeat for the same for other two holes.  The three lines will meet at a point. This point is the centre of gravity of the lamina.

11.  Stability is the ability of an object to regain its original position after it has been displaced slightly.  There are three kinds of equilibrium: 1. Stable Equilibrium 2. Unstable Equilibrium 3. Neutral Equilibrium  Check the examples on the board.

12.  The position of centre of gravity affects the stability of a body. In our daily life, we always need to increase the stability of different objects.  To increase the stability of an object: 1. The centre of gravity should be as low as possible. 2. The base area should be as large as possible.

13.  Wish you all very good luck and excellent result.