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Solve this: •n expe.nrnent to F. NUMERICAL PROBLEMS Z A mass 50 kg stands on ground wearing heels Calculate the pressure exerted by her on the ground area 1 kgf• ION) (Ans. 109 Pa) J. A of wood is floating in water. The block *'Side water measures 50 cm 50 cm 50 cm. What is the magnitude of the buoyant force acting the block? (Take density of water as 1 g cm-3) (Ans. 125 N) 4. The volume of 50 g of a substance is 20 If the density of water is 1 g cm-3 . will the substance noat or sink in water ? Justify your answer (Ans Sink) S. The mass of a block made Of certain material is 13.5 kg and its volume is 15*10-3 m3u Will the block float or sink in water- (Given that density of Water is 1000 kg r•n-') (Ans. Float) 5. The volume of 50 g of a substance is 20 cm'. If the densty of water is 1 g cm-•. will the substance float or sink in water? Justify your answer (Ans_ Sink) . Two spheres A and B, each Of volume 100 crn3 are placed in water (d -1.0 g crn•). The sphere A is made up Of wood Of density 0.3 g c.m-3 and the sphere is made up of iron of density 7.9 g cm-3. Find: (a) Weight of each sphere (b) upthrust on each sphere (c) Which sphere will float and why? (Ans, (a) gf, 790 gf. (b) 100 gf. (C) block A. as weight less than upthrustJ 8. A body of mass 4.5 kg displaces 200 cm3 of water when fully immersed inside it Calculate: (a) The volurne of the body (b) Upthrust on body (c) Apparent weight of body in water (Ans (a) 200 cm'(b) 2 kgf(c) 2S kgf) 9. Four balls are made of different materials: one is solid wood. another iron, another glass and the last is hollow and made of rubber. They all have the same outer radius They are wholly immersed in water use . and/or to express the relation the symbols > the upthrusts F2 F3 and F') exerted on each ball by the surrounding water 10. A solid body of weight 9.0 N is suspended by a string in water The tension in the string is 7.5 Find (a) the loss of weight of the solid in water. (b) the buoyant force exerted by water on the solid, 11. 13. 14. 15. 16. 17. 18. 19. to the (c) the volume of the body and the in string if Only halt the volume Of the body immersed in water Take the density of 10 ISN, An iron cube. mass 480 g and density 8.0 g Suspended half immersed in an Oil of density 0.90 gcm-• (a) Find the buoyant force exerted on iron cube by the oil it. (b) Fhd the tension the N. 453 N) A piece of marble weighs 1.00 N in air and 0.88 N when totany •rnmersed in water. Cak•Aate the vc*.rne of the mart*e and Its Take g 001 N g-' 10 N kg-l and density of water 100 g A cube of wood of Side 10 cm floats in water with cm Of its depth the surface. and With its sides vertical What is the density of wood? Density ( Ans, 450 kg rn¯ä) Of water • IOS kgm-3. A balloon Of VOIurne 2" m'. is with hydrogen Of density 0.09 Kg The mass Of the fabnc iS 100 kg. The mass of the pilot is 70 ky What is the greatest mass of equipment that can be carried When operating in air Of density I .25 kg m ( 2150 kg) A solid block Of wood Ot density 600 kg weighs 306 N in air. Determine (a) the volume Of the block and (b) volume imrnersed when it floats freely in Oil Of density 0,90 g cm•. Express your answer in SI and cgs unts_ Ans 5. I 10-• m 510 cmS and 3.4 340 ) A rubber ball floats in water with 1/3 Of its volume above the water surface. Calculate its average relative (Ans. 087) density. A block ot waxi is floating in water (of density 1 g an-3) with half its volume above the surface When floated in another liquid 1/3 rema.ns above its surface. Calculate the density Of wood and that Of the liquid. ( Ans 0.5 g cm-3 075 g cm-3) The mass of a block is 1.35 kg and its volume is 1 S 10-3 m•. Find the density of the block. Will this block float in water? Give your reason. ( Ans 900 kg ) A solid of density 5000 kg weighs 0.5 kg in air. It is completely immersed in a liquid of density 8000 kg rn-2 Calculate the apparent weight of the solid in the liquid. (Ans. 0.42 kg f) Chapter 4 Fbatatim 4.29

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pressure= force taken out by body
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Try to do the numericals on your own. They are easy. Remember basics of flotation
  • p=  change in force/change in area
  • density =mass/volume
  • p=rho*g*h
  • buoyant force=upthrust=volume of liquid displaced(archimedes principle)
  • specific gravity or  relative density

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