Welcome to your Density and Pressure(Senior Class Physics Study by Topics) NAME EMAIL PHONE NUMBER 1. A piece of wire gauze can be made to lie on water because the wire gauze is less dense than water the water surface has the effect of an elastic thin skin of the cohesive forces between the water and the wire gauze molecules the water molecules repel the wire gauze upward2. In which of the following is surface tension important? the floating of a ship in water the floating of dry needle in water the floating of balloon in air the diffusion of sugar solution across a membrane3. Mercury forms little balls when it is spilled on a bench because it has a high density is very viscous has a high surface tension adheres to the bench is a liquid metal4. When the temperature of a liquid is increased, its surface tension. remains constant decreases increases increases then decreases5. A pilot records the atmospheric pressure outside the plane as 63cm of Hg while a ground observer records a reading of 75cmHg for the atmospheric pressure on the ground. Assuming that the density of the atmosphere is constant, calculate the height of the plane above the ground. (Relative density of Hg = 13.0 and of the air = 0.00013). 6,300m 12,000m 13,800m 7,500m6. A mercury barometer, with a tube of uniform diameter and length of 850mm above the mercury level in the reservoir, reads 750mm on a day when the atmospheric pressure is 760mmHg. What will be the atmospheric pressure on a day when it reads 730mm. 738.3mm 100mm 765.8mm 130mm7. If a fluid flows out of a narrow tube at a depth h below the surface, its velocity is 2gh √2gh gh √2ghρ hρg8. A steel needle floating on the surface of water sinks when kerosene is added to the water because kerosene causes a decrease in the surface tension of water a steel needle is denser than kerosene kerosene causes an increase in the surface tension of water kerosene causes a decrease in the density of water kerosene causes an increase in the density of water9. An object of mass 400g and density 600kg/m³ is suspended with a string so that half of it is immersed in paraffin of density 900kg/m³. The tension in the string is 3N 5N 1N 4N10. The pressure at any point in a liquid at rest depends only on the quantity and the surface area mass and the volume surface area and the viscousity depth and the density11. 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 0.2N/m² 20N/m²12. 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 1m 10m 100m13. The diagram is of a faultless simple mercury barometer. Which of the following is NOT correct? as the barometer is taken up a mountain, h, decreases if the tube is tilted, the vertical height of the mercury column will change the height of the column will not be the same if another liquid is used instead of mercury the atmospheric pressure supports a column of mercury, h a vacuum exists above the mercury in the tube14. Which of the following cannot be correctly explained using the concept of surface tension? crawling of insects on the surface of a pond formation of soap bubbles floating of balloon in the air formation of spherical droplets when water drips from a tap15. Which of the following explains the concave meniscus of water in glass tube? the molecules of water near the glass are moving faster than the molecules in the other parts the cohesion between water molecules is greater than the adhesion between glass and water the molecules of water at the water-air boundary are often attracted to the center of the tube the adhesion between water and glass is greater than the cohesion between water molecules the weight of the water pulls the central part of the surface down16. A test tube of radius 1.0cm is loaded to 8.8g. If it is placed upright in water, find the depth to which it would sink. (g = 10m/s², density of water = 1000kg/m³) 25.5cm 28.0cm 2.8cm 5.2cm17. Water and kerosene are drawn respectively into two limbs of a Hare's apparatus. Density of water is 1.0g/cm³ and the density of kerosene is 0.80g/cm³. If the height of the water column is 20.0cm, calculate the height of the kerosene column. 20.8cm 16.0cm 25.0cm 1.6cm 20.0cm18. I. massII. densityIII. temperatureIV. nature of substanceWhich of the above affects diffusion? none of the above I & II only all of the above II, III & IV only I, II & IV only19. A metal cube of volume 10³mm³ is lowered into a measuring cylinder containing water. If the internal cross-sectional area of the cylinder is 1.5 x 10²mm², by how much does the water level rise in the cylinder? 2500mm 6.67mm 8500mm 150000mm 1150mm20. A uniform cylindrical block of wood floats in water with one-third of its length above the water level. In a liquid of R.D 0.8, what fraction of its height would be above the liquid level? 5/6 4/5 1/3 1/5 1/621. What is the total pressure in cmHg at a point 15m below the surface of a fresh water reservoir. Atmospheric pressure, 76cmHg, density of mercury is 13.6g/cm³ 186cm 18.6cm 1860cm 1.86cm22. A thin hydrometer floats stationary in water at a temperature of about 20ºc. If the water is gradually cooled to 0ºc, their hydrometer will. neither rise nor fall but remains at a constant level rise gradually at first and becomes stationary after some time rise gradually at first then begins to sink slowly sink gradually at first and become stationary after some time oscillate gradually in a vertical plane as long as the cooling continues23. Why does a piece of cork float on water? there is no upthrust on it when completely immersed in water the upthrust on it when completely immersed in water in greater than its weight in air its specific gravity is the same as that of water the upthrust on it when completely immersed in water is less than its weight in air its specific gravity is greater than that of water24. Water does not drip through an open umbrella of silk material unless the inside of the umbrella is touched.Which of the following phenomenon is responsible for this? osmosis viscousity hydrostatic upthrust surface tension diffusion25. Mercury is a better barometric fluid than water becauseI. it needs no colouringII. its density is many times greater than that of waterIII. it does not wet glassIV. it has a high boiling point. III & IV only I, II & III I & II only II only26 out of 25Time is Up!