1. DENSITY FORMULA Density = Mass m Volume v Units g/ml, g/cm3, g/cc Remember 1 ml = 1 cm3 = 1 cc

2. C 3. Archimedes' Principle is named after ARCHIMEDES OF SYRACUSE "who first discovered this law 4. upthrust Archimedes Principle 5. The buoyant force acting on an object depends upon two factors: The volume of the body immersed i.e. volume of the fluid displaced ,or density of the fluid 6. APPARENT LOSS IN WEIGHT = True weight-weight of the body immersed in a fluid (=buoyant force) = w1-w2 7. BUOYANT FORCE =apparent loss in weight-true weight(w1) 8. VERIFYING ARCHIMEDES PRINCIPLE Take an Eureka can and fill it up to its spout. Take a stone and suspend it with the hook of the spring balance.Note the weight of stone in air.Let it be w1. Now immerse the stone inside water in the Eureka can.the water overflows through the can.Collect this overflowing water in the beaker. Now also note the reading in the spring balance.Let it be w2 9. This w2 will be less than w1 due to upthrust provided by water.Apparent loss in weight due to upthrust will be (w1-w2) Measure the weight of water collected in the beaker , which in fact is the weight of water displaced by the stone . On comparing we will found that the loss in weight (w1-w2 )is equal to the weight of the water displaced by the stone.Hence the Archimedesprinciple is verified. upthrust apparent loss in weight is equal to the weight of the fluid displaced by the immersed part of the body 10. WHERE WILL THEY FLOAT? salt water density= 1.2 g/cc fresh water density= 1.0 g/cc oil density= 0.9 g/cc Object A: density= 0.8 g/cc Object B:density= 0.95 g/cc Object C:density = 1.1 g/cc Object D:density= 1.3 g/cc Object E:density= 4.0 g/cc 11. A ship is hollow at the bottom because of which its average density is lees than that of water so the ship is able to displace water equal to its weight and hence it 12. If the submarine has to come up,the tanks are emptied out ,so the weight of the submarine decreases in comparison to the weight of the water displaced and the submarine rises up to the surface 13. THE FISHES Some species of fishes have swim bladder. When fishes want to rise they fill this bladder with gases diffused from their own body. Thus becoming lighter and to go down they empty their bladder thereby increasing their density and hence manage to sink 14. Hydrogen and Helium filled balloons and hot air balloons tend to move upwards because the density of hydrogen is about 1/4th of the air. The upward force is more than the downward force of the balloon and hence it rises upwards till the density of both becomes same