UNIT 3.3:-PRESSURE FROM THE AIR Let’s look at how air can exert pressure even though we can’t see it. LEARNING OBJECTIVES 9Pf3 Explain pressures in gases and liquids (qualitative only). Understanding the properties of pressure in air Learning the concept of atmospheric pressure and its standard value. Understanding the functioning of a Barometer to measure the atmospheric pressure. Learning how we can use the manometer to measure the pressure difference between gases. STARTER QUESTIONS (PEER CHECK) :1. Does pressure exist in all states of matter? Explain why? 2. How does pressure exerted by solids differ from that exerted by liquids? 3. Mention the ways in which pressure exerted by solids can be altered. 4. Mention the ways in which the pressure exerted by liquids can be altered. 5. Write down the pressure equation of solids and then of liquids? ANSWERS :1. Yes, pressure is exerted from all states of matter as they all are made up of particles. The vibration or motion of these particles exert pressure on the surfaces. 2. Pressure in solids are exerted on the surfaces the particles are in contact with, like the bottom of the book with exert pressure on the top of the table. Pressure of liquids acts in all direction as the particles are moving and colliding in all directions. 3. By changing the area the force is applied on and also by changing the force ( if possible) 4. By changing the type of liquid ( changing density) and by altering the height of the liquid. 5. SOLID LIQUID https://www.youtube.com/ watch?v=KndNN28OcEI What are the two properties of Air can you see that are found in liquids? ANALYZE AND EXPLAIN WHY IN ONE LINE WHAT HAPPENS TO YOUR FINGER? LETS LOOK AT A BAROMETER HTTPS://WWW.YOUTUBE.COM/WATCH?V=JDBWOAFXC EA 1atm = 760 mm ( Barometer) 1atm = 101 300Pa 1mb=100 Pa HOME LEARNING (TIMMS) Research on the difference between weather and climate and how both are affected by the changing air pressure and temperatures of the earth’s atmosphere. Include also the effects that the position of a country on the globe and the continuing global warming is having on the conditions of the present weather and climate around the world.