4.(a) Why does a solid body weigh more in air than when immersed in a liquid?
(b) An ordinary hydrometer of mass 27 g floats with 4 cm of its stem out of water. If the cross sectional area of the stem is 0.75 cm2 calculate:
(i)the total volume of the stem just under the surface of the liquid.
(ii)the relative density of the liquid.
(c) (i) What do you understand by resolution of a force?
(ii) A metre rule is pivoted at its mid-point. If two objects of weights 1.0 N and 2.0 N are suspended at 30 cm and 90 cm respectively from one end, calculate the position where an upward force of 3.0 N must be applied in order for the metre rule to balance horizontally.
(b) Two stones are thrown vertically upwards from the same point with the same velocity of 20 m/s but at an interval of 2 seconds. When they meet, the second stone is rising at 10 m/s. Calculate:
(i) the time taken by the second stone in air before they meet (ii) the velocity of the second stone when they meet.
(c) A stationary bomb of mass 5 kg explodes into one part A of mass 2 kg flying off with a velocity of 60 m/s and another part B of mass 3 kg flying off with a certain velocity in the opposite direction. Calculate the
(i)velocity of part B
(ii)total kinetic energy produced by the explosion.
11.(a) State the application of each of the following apparatus:
(i) Manometer (ii) Hygrometer
(b)(i) What is a siphon?
(ii)With the help of a labeled diagram explain the principle on which the siphon operates.
(c)(i) Briefly explain why a bubble of air increases in volume as it rises from the bottom of a pond to the surface.
(ii)A uniform tube 1.0 m long and closed at its upper end is pushed vertically downward into mercury until the liquid rises 0.2 m inside the tube. Calculate the depth of the open end below the mercury surface.