JEE Main 2022 (Online) 28th June Morning Shift | Properties of Matter Question 123 | Physics

A water drop of diameter 2 cm is broken into 64 equal droplets. The surface tension of water is 0.075 N/m. In this process the gain in surface energy will be :

2.8 $$\times$$ 10^$$-$$4 J

1.5 $$\times$$ 10^$$-$$3 J

1.9 $$\times$$ 10^$$-$$4 J

9.4 $$\times$$ 10^$$-$$5 J

JEE Main 2022 (Online) 27th June Evening Shift

MCQ (Single Correct Answer)

-1

When a ball is dropped into a lake from a height 4.9 m above the water level, it hits the water with a velocity v and then sinks to the bottom with the constant velocity v. It reaches the bottom of the lake 4.0 s after it is dropped. The approximate depth of the lake is :

19.6 m

29.4 m

39.2 m

73.5 m

JEE Main 2022 (Online) 27th June Morning Shift

MCQ (Single Correct Answer)

-1

The velocity of a small ball of mass 'm' and density d₁, when dropped in a container filled with glycerin, becomes constant after some time. If the density of glycerin is d₂, then the viscous force acting on the ball, will be :

$$mg\left( {1 - {{{d_1}} \over {{d_2}}}} \right)$$

$$mg\left( {1 - {{{d_2}} \over {{d_1}}}} \right)$$

$$mg\left( {{{{d_1}} \over {{d_2}}} - 1} \right)$$

$$mg\left( {{{{d_2}} \over {{d_1}}} - 1} \right)$$

JEE Main 2022 (Online) 26th June Evening Shift

MCQ (Single Correct Answer)

-1

If p is the density and $$\eta$$ is coefficient of viscosity of fluid which flows with a speed v in the pipe of diameter d, the correct formula for Reynolds number R_e is :

$${R_e} = {{\eta d} \over {\rho v}}$$

$${R_e} = {{\rho v} \over {\eta d}}$$

$${R_e} = {{\rho vd} \over \eta }$$

$${R_e} = {\eta \over {\rho vd}}$$

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