1
JEE Main 2018 (Online) 16th April Morning Slot
+4
-1
A small soap bubble of radius 4 cm is trapped inside another bubble of radius 6 cm without any contact. Let P2 be the pressure inside the inner bubble and P0, the pressure outside the outer bubble. Radius of another bubble with pressure difference P2 $$-$$ P0 between its inside and outside would be :
A
12 cm
B
2.4 cm
C
6 cm
D
4.8 cm
2
JEE Main 2018 (Offline)
+4
-1
A solid sphere of radius r made of a soft material of bulk modulus K is surrounded by a liquid in a cylindrical container. A massless piston of area a floats on the surface of the liquid, covering entire cross section of cylindrical container. When a mass m is placed on the surface of the piston to compress the liquid, the fractional decrement in the radius of the sphere, $$\left( {{dr \over r}} \right)$$ is:
A
$${{mg} \over {Ka}}$$
B
$${{Ka} \over {mg}}$$
C
$${{Ka} \over {3mg}}$$
D
$${{mg} \over {3Ka}}$$
3
JEE Main 2018 (Online) 15th April Evening Slot
+4
-1
When an air bubble of radius r rises from the bottom to the surface of a lake its radius becomes $${{5r} \over 4}.$$ Taking the atmospheric pressure to be equal to 10 m height of water column, the depth of the lake would approximately be (ignore the surface tension and the effect of temperature) :
A
11.2 m
B
8.7 m
C
9.5 m
D
10.5 m
4
JEE Main 2018 (Online) 15th April Evening Slot
+4
-1
The value closest to the thermal velocity of a Helium atom at room temperature (300 K) in ms-1 is :
[kB =1.4 $$\times$$ 10-23 J/K; mHe = 7 $$\times$$ 10 -27 kg ]
A
1.3 $$\times$$ 104
B
1.3 $$\times$$ 103
C
1.3 $$\times$$ 105
D
1.3 $$\times$$ 102
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