27/03/2020Density and Pressure(Senior Class Physics Study by Topics) 0Comments by Gate Academy Welcome to your Density and Pressure(Senior Class Physics Study by Topics) NAME EMAIL PHONE NUMBER 1. A spiral spring, loaded with a piece of metal, extends by 10.5cm in air. When the metal is fully submerged in water, the spring extends by 6.8cm. Calculate the relative density of the metal. (Assume Hooke's law is obeyed) 3.84 17.3 10.5 3.72. Two divers G & H are at depths 20m & 40m respectively below the water surface in a lake. The pressure on G is P1 while the pressure on H is P2 . If the atmospheric pressure is equivalent to 10m of water, the value of P2 /P1 is 2.00 3.00 60 1.67 0.503. Oil from a bottle flows out more easily after it has been warmed because cohesion between the oil molecules and those of the bottle is reduced molecules are given potential energy during warming friction between the oil layer is reduced osmotic pressure of the oil is increased oil molecules force one another out4. It is observed that water will wet a clean glass because the adhesion of water molecules is weaker than the cohesion of water to glass adhesion of water molecules is stronger than the cohesion of water molecules cohesion of water to glass is weaker than the cohesion of water molecules cohesion of water to glass is stronger than the cohesion of water molecules5. A cube of side 10cm and mass 0.5kg floats in a liquid with only one-fifth of its height above the surface of the liquid. What is the R.D of the liquid? 0.625 0.125 2.500 0.2506. A thin hydrometer floats stationary in water at a temperature of about 20ºc. If the water is gradually cooled to 0ºc, their hydrometer will. sink gradually at first and become stationary after some time rise gradually at first then begins to sink slowly oscillate gradually in a vertical plane as long as the cooling continues rise gradually at first and becomes stationary after some time neither rise nor fall but remains at a constant level7. A balloon whose volume is 300m³ is filled with hydrogen. If the density of air is 1.3kg/m³, find the upthrust on the balloon 4,200N 3,900N 3,800N 3,000N8. The pressure at any point in a liquid at rest depends only on the surface area and the viscousity depth and the density quantity and the surface area mass and the volume9. In which of the following is surface tension important? the floating of dry needle in water the diffusion of sugar solution across a membrane the floating of balloon in air the floating of a ship in water10. A well 1km deep is filled with a liquid of density 950kg/m³. If the atmospheric pressure is 100000N/m² and g = 10m/s², the pressure at the bottom of the well is 20000N/m² 9,400,000N/m² 950,000N/m² 9,600,000N/m² 11. At what depth below the sea-level would one experience a change of pressure equal to one atmosphere? (density of sea water = 1013kg/m³; one atm = 101,000N/m²; g = 10m/s²) 100m 1m 10m 0.1m12. Which of the following statements is/are correct about the common hydrometer?I. it has a long narrow stemII. the R.D values marked on the stem increases down the stemIII. it has a wide bulbIV. the bulb is loaded to make the hydrometer float vertically II & IV only II only I, III & IV only I, II & III only I, II, III & IV13. If the relative density of a metal is 19. What will be the mass of 20cm³ of the metal when immersed in water? 39g 360g 180g 380g 400g14. A heavy object is suspended from a string and lowered into water so that it is completely submerged. The object appears lighter because it experiences an upthrust the pressure is low just below the water surface the tension in the string neutralizes part of the weight the density of water is less than that of the object15. Which of the following cannot be correctly explained using the concept of surface tension? floating of balloon in the air formation of spherical droplets when water drips from a tap crawling of insects on the surface of a pond formation of soap bubbles16. A parachute attains a terminal velocity when the viscous force of the air is equal to the sum of the weight and upthrust its density is equal to the density of air the viscous force of the air and the upthrust completely counteract its weight it expands as a result of reduced external pressure17. Which of the following is obeyed if a force on a sphere moving through a viscous fluid is proportional to its speed, radius and viscosity? Archimedes' principle Stoke's law Bernoulli's law Pascal's principle18. The accurate measurement of the relative density of substances in powder or granular form can be done using a beam balance and a ? measuring cylinder eureka can biurette pipette density bottle19. For accurate measurement of atmospheric pressure, it is preferable to use which of the following instrument. mercury manometer pressure gauge fortin barometer water manometer20. The terminal velocity of a ball-bearing falling through a viscous fluid is reached when the velocity is uniform upthrust is equal to the velocity of the ball ball accelerates uniformly upthrust is equal to the weight of the ball21. The mass of a specific gravity bottle is 15.2g when empty. It is 24.8g when filled with petrol and 27.2g when filled with distilled water. Calculate the R.D of petrol. 1.10 0.80 0.90 1.2522. By which of the following processes does a piece of blotting paper absorbs a drop of ink from a sheet of writing paper? the action of the force of viscousity between the molecules of the ink the action of the forces of cohesion between the molecules of the blotting paper fibres the diffusion of the ink into the blotting paper fibres the action of the forces of cohesion between the blotting paper fibres and the ink the capillarity rise of the ink into the blotting paper fibres23. The water manometer in the diagram below is measuring the pressure of the gas supply. If the specific gravity of mercury is 13.6 and the atmospheric pressure is 70cmHg, what is the total pressure of the gas supply in cm of water? 67cm 949cm 73cm 955cm 952cm24. A balloon of volume 100m³ and mass 2kg is filled with helium of density 0.18kg/m³ at ground level. The surrounding air has a density of 1.28kg/m³. Calculate the maximum mass which the balloon can lift off the ground. 120kg 108kg 85kg 128kg25. A rectangular solid block has length 10cm, breadth 5cm and height 2cm. If its lies on a horizontal surface and has density 100kg/m³, calculate the pressure it exerts on the surface. 200N/m² 2N/m² 20N/m² 0.2N/m²26 out of 25Time is Up!