1
WB JEE 2024
+2
-0.5

A metal plate of area $$10^{-2} \mathrm{~m}^2$$ rests on a layer of castor oil, $$2 \times 10^{-3} \mathrm{~m}$$ thick, whose coefficient of viscosity is $$1.55 \mathrm{~Ns} \mathrm{~m}^{-2}$$. The approximate horizontal force required to move the plate with a uniform speed of $$3 \times 10^{-2} \mathrm{~ms}^{-1}$$ is

A
0.6718 N
B
0.2325 N
C
0.2022 N
D
0.6615 N
2
WB JEE 2023
+1
-0.25

As shown in the figure, a liquid is at same levels in two arms of a U-tube of uniform cross-section when at rest. If the U-tube moves with an acceleration 'f' towards right, the difference between liquid heights between two arms of the U-tube will be, (acceleration due to gravity = g)

A
$$\mathrm{\frac{f}{g}a}$$
B
$$\mathrm{\frac{g}{f}a}$$
C
$$\mathrm{a}$$
D
0
3
WB JEE 2023
+1
-0.25

As shown in the figure, a pump is designed as horizontal cylinder with a piston having area A and an outlet orifice having an area 'a'. The piston moves with a constant velocity under the action of force F. If the density of the liquid is $$\rho$$, then the speed of the liquid emerging from the orifice is, (assume $$\mathrm{A} > >$$ a)

A
$$\sqrt{\frac{F}{\rho A}}$$
B
$$\frac{a}{A} \sqrt{\frac{F}{\rho A}}$$
C
$$\sqrt{\frac{2 F}{\rho A}}$$
D
$$\frac{A}{a} \sqrt{\frac{2 F}{\rho A}}$$
4
WB JEE 2022
+1
-0.25

27 drops of mercury coalesce to form a bigger drop. What is the relative increase in surface energy?

A
$${3 \over 2}$$
B
$${2 \over 3}$$
C
$$-$$$${2 \over 3}$$
D
8
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