Q. a cube of mass 1kg with each side of 1cm is lying on the table. find the pressure exerted by the block on the table. take g=10 m/s2
Ans: Pressure is given as force/area so, Force, F = mg = 1000 X 981 gm.m/s2and area, A = 1x1 cm2 = 1 cm2Thus, the pressure exerted would be P = (981 X 1000) / 1 or
P = 9.81 X 10 5 pa
Q. The mass of a solid iron cube of side 3cm is to be determined usig a spring balance. If the of iron is approximately 8.5 g/cm3, the best suited spring balance for determining weight of the solid would be of
1. range 0-250gwt ; least count 1gwt
2. range 0-250gwt ; least count 5gwt
3. range 0-1000gwt ; least count 5gwt
4. range 0-1000gwt ; least count 10gwt
Ans: Edge=3 cm , Density=8.5 g/cm3Mass= density x volume = 8.5 x(3x3)=229.5gwt
Therefore second spring balance of range 0-250 gwt with least count 5gwt will be suitable.
Q. The density of turpentine oil is 840 Kg/ m3. What will be its relative density. (Density of water at 4 degree C is 10 cube kg minus cube)
Ans:Relative Density = Density of Substance/ Density of water at 4 0cDensity of turpentine oil = 840 kg/ m3 ( given).Density of water at 4 0c = 1000 kg/ m3Relative density of turpentine oil = Density of turpentine oil / Density of water at 4 0c= (840 / 1000 ) kg m-3/ kg m-3 = 0.84Since, the relative density of the turpentine oil is less than 1, therefore it will float in water.
Q. A solid body of mass 150 g and volume 250cm3 is put in water . will following substance float or sink if the density of water is 1 gm-3?
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