1
JEE Main 2022 (Online) 27th June Evening Shift
+4
-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 :

A
19.6 m
B
29.4 m
C
39.2 m
D
73.5 m
2
JEE Main 2022 (Online) 27th June Morning Shift
+4
-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 :

A
$$mg\left( {1 - {{{d_1}} \over {{d_2}}}} \right)$$
B
$$mg\left( {1 - {{{d_2}} \over {{d_1}}}} \right)$$
C
$$mg\left( {{{{d_1}} \over {{d_2}}} - 1} \right)$$
D
$$mg\left( {{{{d_2}} \over {{d_1}}} - 1} \right)$$
3
JEE Main 2022 (Online) 26th June Evening Shift
+4
-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 Re is :

A
$${R_e} = {{\eta d} \over {\rho v}}$$
B
$${R_e} = {{\rho v} \over {\eta d}}$$
C
$${R_e} = {{\rho vd} \over \eta }$$
D
$${R_e} = {\eta \over {\rho vd}}$$
4
JEE Main 2022 (Online) 25th June Morning Shift
+4
-1

The terminal velocity (vt) of the spherical rain drop depends on the radius (r) of the spherical rain drop as :

A
r1/2
B
r
C
r2
D
r3
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