1. T HRUST & P RESSURE 1 Creative Commons License Content Sourced and Aggregated by Centre for Positive Learning Supported by TCS iON Learning Exchange  Activity  Assess Knowledge Class IX / Term II / science

2. A CTIVITY Topic To study ARCHIMEDES PRINCIPLE Objective Objects of density less than that of a liquid float on the liquid. The objects of density gr eater than that of a liquid sink in the liquid 2 Class IX / Term II / science

3. A CTIVITY C ONTD … Pre-requisite Knowledge Archimedes principle states that "When a body is partially or completely immersed in a fluid, the fluid exerts an upward force on the body equal to the weight of the fluid displaced by the liquid". Materials required Stone, Rubber string or a spring balance. Water in a container. 3 Class IX / Term II / science

4. A CTIVITY C ONTD … Steps to perform the activity Take a piece of stone and tie it to one end of a rubber or a string balance. Suspend the stone by holding the balance or the string as shown in Fig (a). Note the elongation of the string or the reading on the spring balance due to the weight of the stone. Now, slowly dip the stone in the water in a container as shown in Fig. (b) Observe what happens to the elongation of the string or the reading on the balance. 4 Class IX / Term II / science

5. A CTIVITY C ONTD … Demonstration 5 Class IX / Term II / science

6. A CTIVITY C ONTD … Conclusion As the stone slowly dipped into the water, it will experience an up thrust. This will decrease the weight of the stone which in turn will decrease the elongation of the string or the reading on the balance. This decrease in elongation or balance reading will continue as more and of the stone is dipped into water. 6 Class IX / Term II / science

7. A SSESS K NOWLEDGE CCE Questions (5 Marks) Define the term thrust and state its unit. 7 Class IX / Term II / science