[" An electric fan,with effective area of cross- "],[" section 'A',accelerates air of density "^(6)rho" ' to a "],[" speed 'v'.What is the power needed for this "],[" process? "]

An electric fan, with effective area of cross-section 'A', accelerates air of density 'rho' to a speed 'v'. What is the power needed for this process ?

What is the effect on resistance, if the area of cross section is increased.

The vessel shown in the figure has two sections of areas of cross-section A _ 1 and A _2 . A liquid of density rho fills both the section, up to a height h in each. Neglect atmospheric pressure. Choose correct options.

If a solid cylinder of area of cross-section A is moving with velocity V in medium of density p then power loss of cylinder is

If a solid cylinder of area of cross-section A is moving with velocity V in medium of density p then power loss of cylinder is

A conductor of length l, area of cross section A and resistivity rho has resistance = R. It is connected across a cell of voltage V . What will be the current flowing resistor if its length is doubled and cross section area is halved.

A motor pump a liquid of density rho through a pipe of cross-sectional area A. If the liquid moves with a speed v in this pipe, then the rate of kinetic energy imparted to the liquid is proportional to