1
JEE Main 2019 (Online) 10th April Morning Slot
+4
-1
The ratio of surface tensions of mercury and water is given to be 7.5 while the ratio of thier densities is 13.6. Their contact angles, with glass, are close to 135° and 0°, respectively. It is observed that mercury gets depressed by an amount h in a capillary tube of radius r1, while water rises by the same amount h in a capillary tube of radius r2. The ratio, (r1/r2), is then close to :
A
2/5
B
2/3
C
3/5
D
4/5
2
JEE Main 2019 (Online) 9th April Evening Slot
+4
-1
A wooden block floating in a bucket of water has 4/5 of its volume submerged. When certain amount of an oil is poured into the bucket, it is found that the block is just under the oil surface with half of its volume under water and half in oil. The density of oil relative to that of water is :-
A
0.8
B
0.7
C
0.6
D
0.5
3
JEE Main 2019 (Online) 9th April Evening Slot
+4
-1
Two materials having coefficients of thermal conductivity '3K' and 'K' and thickness 'd' and '3d', respectively, are joined to form a slab as shown in the figure. The temperatures of the outer surfaces are '$$\theta$$2' and '$$\theta$$1' respectively, ($$\theta$$2 > $$\theta$$1). The temperature at the interface is :-
A
$${{{\theta _1}} \over {10}} + {{9{\theta _2}} \over {10}}$$
B
$${{{\theta _2} + {\theta _1}} \over 2}$$
C
$${{{\theta _1}} \over {6}} + {{5{\theta _2}} \over {6}}$$
D
$${{{\theta _1}} \over {3}} + {{2{\theta _2}} \over {3}}$$
4
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
A simple pendulum oscillating in air has period T. The bob of the pendulum is completely immersed in a non-viscous liquid. The density of the liquid is 1/16 th of the material of the bob. If the bob is inside liquid all the time, its period of oscillation in this liquid is :
A
$$2T\sqrt {{1 \over {10}}}$$
B
$$4T\sqrt {{1 \over {14}}}$$
C
$$4T\sqrt {{1 \over {15}}}$$
D
$$2T\sqrt {{1 \over {14}}}$$
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