27/03/2020 Density and Pressure(Senior Class Physics Study by Topics) 27/03/2020 0Comments by Gate Academy Welcome to your Density and Pressure(Senior Class Physics Study by Topics) NAME EMAIL PHONE NUMBER 1. 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. 128kg 120kg 85kg 108kg 2. Mechanical pumps cannot move fluids in a horizontal direction compress gases in a container move fluids in a vertical direction decrease the pressure in an enclosure increase the atmospheric pressure 3. A solid weighs 6.4N in air, 5.4N in water and 5.6N in kerosene. Calculate the relative density of kerosene. 0.60 0.50 0.75 0.80 4. A cube of glass of 5cm side and mass 306g has a cavity inside it. If the density of glass is 2.55g/cm³, what is the volume of the cavity? 5cm³ 50cm³ 125cm³ 120cm³ 5. Which of the following factors influence the rate of flow of water through a pipe to houses?I. the material of the pipeII. the diameter of the pipeIII. the viscosity of the water II & III only I, II & III I & III only I & II only 6. A hose ejects water at a speed of 15cm/s through a hole of area 75cm². If the water strikes a wall normally, calculate the force on the wall. (Assuming that the velocity of water after striking the wall is zero and density of water = 1000kg/m³). 0.169N 0.676N 0.338N 0.507N 7. The hatch door of a submarine has an area of 0.5m². The specific gravity of sea water is 1.03, assume that g = 10m/s² and neglect the atmospheric pressure, the force exerted by the sea water on the hatch door at the depth of 200m is 10,300N 1,030,000N 1,030N 103,000N 206,000N 8. An open tank holds water 1.25m deep. If a small hole of cross-sectional area 3cm² is made at the bottom of the tank, calculate the mass of water per second initially flowing at the hole (g = 10m/s², density of water = 1000kg/m³) 3kg/s 1.5kg/s 4.5kg/s 5.5kg/s 9. 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) 0.1m 100m 10m 1m 10. Which of the following is suitable to use an altimeter? an Aneroid barometer a mercury barometer a mercury manometer a Fortin barometer 11. A liquid of mass 1000kg fills a rectangular tank of length 2m. If the tank is 4m high, what is the pressure at the middle of the tank? 1,500N/m² 1,000N/m² 10,000N/m² 2,000N/m² 12. 40cm³ of liquid P is mixed with 60cm³ of another liquid Q. If the density of P and Q are 1.00kg/m³ and 1.6kg/m³ respectively, what is the density of the mixture? 1.25kg/m³ 0.05kg/m³ 1.36kg/m³ 1.30kg/m³ 13. If a spherical metal bob of radius 3cm is fully immersed in a cylinder containing water and the water level rises by 1cm. What is the radius of the cylinder? 12cm 1cm 3cm 6cm 14. Which of the following cannot be correctly explained using the concept of surface tension? formation of soap bubbles formation of spherical droplets when water drips from a tap crawling of insects on the surface of a pond floating of balloon in the air 15. Mercury is suitable as a barometric fluid because it is several times denser than water is opaque is a good conductor of heat expands uniformly 16. A man on a bench will exert the greatest pressure on the bench when he lies flat on his belly Stands on the toes of one foot lies flat on his back Stands on one foot only stands on both feet 17. A spherical metal ball falling through a viscous liquid is acted upon by the I. weight of the ballII. viscous force of the liquid on the ballIII. upthrust of the liquid on the ball I & II only I & III only II & III only I, II & III 18. When the temperature of a liquid is increased, its surface tension. increases then decreases increases decreases remains constant 19. Calculate the pressure on Radeyah's thumb when she exerts a force of 20N and the top of the pin is square, the length of each side being 10mm0.2N/mm² 0.2N/mm² 2N/mm² 12N/mm² 20N/mm² 20. In which of the following is surface tension important? the floating of balloon in air the floating of dry needle in water the floating of a ship in water the diffusion of sugar solution across a membrane 21. When a paint brush is removed from clean water, the bristles of the brush are pulled together because of the mass of the brush bristles surface tension low density of water the weight of the brush bristles the viscousity of the surrounding 22. Air was pumped out of a sealed can and the can collapsed. Which of these statements is the best explanation for this? The material used in making the can was very weak Pumping out of the air weakened the can The remaining air inside the can condensed to form water The air pressure inside the can became less than the air pressure outside the can 23. A cube of sides 0.1m hangs freely from a string. What is the upthrust on the cube when totally immersed in water? 10N 110N 1000N 700N 24. A body whose mass is 2kg has a volume of 500cm³ just floats when completely immersed in a liquid. Calculate the density of the liquid 4000kg/m³ 400kg/m³ 1000000kg/m³ 1000kg/m³ 25. A thin hydrometer floats stationary in water at a temperature of about 20ºc. If the water is gradually cooled to 0ºc, their hydrometer will. oscillate gradually in a vertical plane as long as the cooling continues neither rise nor fall but remains at a constant level rise gradually at first then begins to sink slowly sink gradually at first and become stationary after some time rise gradually at first and becomes stationary after some time 1 out of 25 Time is Up! Time's up