Unit-5 Pressure and Deformation in Solids
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Unit-5 Pressure and Deformation in Solids
Answer: Pressure is the force acting perpendicular to a surface per unit area, P = F/A.
Answer: The SI unit of pressure is the pascal, where 1 Pa = 1 N/m^2.
Answer: Pressure equals the applied force divided by the area over which it acts, P = F/A.
Answer: One pascal is one newton of force acting on an area of one square metre.
Answer: P = F/A = 200 N / 0.4 m^2 = 500 Pa.
Answer: Pressure is inversely proportional to area, so a larger area gives smaller pressure for the same force.
Answer: The same force on a smaller area produces a much larger pressure, allowing the knife to cut.
Answer: A larger contact area reduces the pressure so the tractor does not sink into soft soil.
Answer: The tiny area of the point gives a very large pressure from the modest force of the thumb.
Answer: A = F/P = 200 N / 400 Pa = 0.5 m^2.
Answer: Liquid pressure increases with depth because the weight of the liquid above adds to the pressure.
Answer: Hydrostatic pressure P = h x rho x g depends only on depth, liquid density and g.
Answer: At the same depth the liquid transmits pressure equally in all directions.
Answer: Hydrostatic pressure is P = h rho g, where h is depth, rho is density and g is gravity.
Answer: P = h rho g = 2 x 1000 x 10 = 20,000 Pa.
Answer: A barometer measures atmospheric pressure, often using a column of mercury.
Answer: Standard atmospheric pressure supports a mercury column of about 760 mm = 76 cm.
Answer: Higher altitude means less air above, so atmospheric pressure decreases.
Answer: 1 standard atmosphere = 1.013 x 10^5 Pa = 101,300 Pa.
Answer: P = h rho g = 0.76 x 13,600 x 10 = 103,360 Pa, close to standard atmospheric pressure.