1. IGCSE PHYSICS CONDITIONS FOR EQUILIBRIUM By Yaejong Lee

2. Equilibrium When a number of forces acting on a body produce no change in its state of rest, the body is said to be in equilibrium. The sum of the anticlockwise moments about any point must be equal to the sum of the clockwise moments about the same point. http://ap-physics.david-s.org2

3. Conditions for Equilibrium There are two conditions for the body to be in equilibrium 1.) The resultant of all the forces acting on the body should be equal to zero 2.) The resultant moment of all the forces acting on the body about a point should be zero Principle of moment In equilibrium the sum of the clockwise moments about any point must be equal to the sum of the clockwise moments about the same point. This is called the principle of moments http://ap-physics.david-s.org3

4. IGCSE PHYSICS POTENTIAL AND KINETIC ENERGY By Yaejong Lee

5. Potential energy ◦ For example a pulled spring is able to store energy as the result of its position. When not pulled at there is no energy stored in the spring but when the position is altered from its equilibrium position, the spring is able to store energy. This stored energy is referred to as potential energy. Potential energy is the energy stored in an object as a result of it position. http://ap-physics.david-s.org5

6. The mass of the object times the acceleration due to gravity is the weight of an object. Therefor Potential energy is the weight of the object time the height. http://ap-physics.david-s.org6

7. Kinetic energy Kinetic energy depends on the mass of the object as well as the speed of that object. Kinetic energy is the energy of motion. Kinetic (derived from the Greek root word “ kinein” which means “to move”) http://ap-physics.david-s.org7

8. ◦ More at ◦ http://ap-physics.david-s.org/ http://ap-physics.david-s.org8