Particle Model
- 1. By: Metta
- 2. Particles in Solid • Move a little • Do not change position • Vibrate to and fro in their position Particles in Liquid • Weaker than in solid’s • Have some freedom • Can change position by sliding over each other Particles in Gas • Can move away from each other • Travel in all direction • Move freely and in high speed
- 3. Changes in Solid •When a solid is heated it expands and when it cools it contracts. •For example, the apparatus here. When the metal ball is heated, it will expand and when we try to put it in the gauze, it will not fit anymore. But when we try to put it in after about 5-10 minutes, it will fit again.
- 4. Changes in Solid The expansion of materials due to heating must be taken into account whenever materials are likely to encounter changes in temperature Metal pipes carrying hot water in large central heating systems are connected by expansion joints, which allow pipes to lengthen without pushing into each other.
- 5. Changes in Solid The temperature changes due to the weather can also cause expansion and contraction. The end of a bridge may be set on rollers so that as it lengthens it simply moves over its support and does not push into the adjoining roadway.
- 6. Different solids expand by Changes in Solid different amounts for a given temperature rise. This fact also explains why bimetallic strip may be used in a fire alarm. Brass expands more than iron. The picture above informs us that when the bimetallic strip is heated, it bends because the length of the brass strip becomes greater than the iron strip.
- 7. Liquid has a unique fact. It Changes in Liquid expands in between 0°C-4°C. When water has a range of The diagram here shows the temperatures close to 0°C, the colder expansion of liquid. water rises above the warmer water and collects at the surface. This fact is used to explain why the fish beneath a pond in a very cold winter can stay warm and alive.
- 8. Changes in Gas
- 9. Hot Air Balloon 1. When the air in a hot air balloon is heated it expands and fills the balloon. 2. The surrounding air exerts a up-thrust force which is greater than the combined weight of the balloon, basket, pilot and passengers. 3. The density of the surrounding air decreases with an increase in height. The balloon will continue to rise until it reaches air that is sufficiently less dense for the weight and up-thrust to balance.
- 10. Explosion An explosion occurs when a gas is made to expand very strongly and very quickly. This creates large forces that push everything around. Explosives are used in quarries – the force of the expansion is strong enough to break up rocks.
- 11. Car Cylinder A car engine has cylinders in which small explosions occur. A mixture of air and petrol vapor is ignited by a spark plug, and the hot gases, which expand quickly, push down a piston. The downward force of the piston is changed into a turning force by other parts of the engine, and this is used to turn the car’s wheels.
- 12. Melting and Boiling Melting In a solid the particles are held firmly together but as they get hotter, they come to vibrate so strongly that they began to slide over each other. When this occurs, the solid has melted and become a liquid. The temperature at which a solid melts is called the melting point.
- 13. Melting and Boiling Boiling As a liquid receives more and more heat, its particles become more and more active. Eventually they become more active that they lose their grip of each other and become a gas. This can occur at the surface if the liquid or inside the liquid where the gas particles form bubbles. This process of forming bubbles is called boiling, and the temperature at which it occurs is called the boiling point of the liquid.
- 14. Thank You For Your Attention!