Power

A person of mass $100 \mathrm{kg}$ reaches a height in $10 \mathrm{seconds}$. Find the power used by the person ($g=10 \raisebox{1ex}{$\mathrm{m}$}\!\left/ \!\raisebox{-1ex}{${\mathrm{s}}^2$}\right.$).

A boy of mass $50 \mathrm{kg}$ runs a stair case of $45$ steps in $9 \sec$. If the height of each steps is $15 \mathrm{cm}$, find his power. (Take $\mathrm{g}=10 {\mathrm{ms}}^{-2}$).

A water pump lifts water from a level $10 \mathrm{m}$ below the ground. The water is pumped at the rate of$30 \mathrm{kg}/\min$ with negligible velocity. Calculate the minimum power the pump should have to do this work.

You have the following appliances each of 500 W running on 220 V ac.

Two heaters, each marked 1000 W, 250V are connected in series with a 250 V supply. Assuming that their resistance remains constant, their combined rate of heating will be

Five equal resistors when connected in series dissipated 5 W power. If they are connected in parallel, the power dissipated will be

Two electric bulbs A and B are designed for the same voltage. Their power ratings are PA and PB respectively with PA<PB If they are joined in series across a V-volt supply

If R1 and R2 are the filament resistances of a 200 W and a 100 w bulb respectively, both designed to run at the same voltage, then

Heat developed in an electric wire of resistance R ohm by current l ampere for a timer t second is

A 2 KW boiler used for 1 hour everyday consumes the electrical energy for the whole month of April. The number of units consumed is

Two bulbs, one of $200 W/220V$ and the other of $100 W/220 V$, are connected in series with a $100 V$ battery which has internal resistance. Then

What should be the power of the Motorboat if it is desired to get a steady speed of 72 km/h we know that resistance by water is of the order of 5000 N N 

When water is flowing through a pipe with a speed of$V$, then its power is proportional to

An electric bulb is designed to draw $P_0$ power at $V_0$ voltage. If the voltage is V, it draws P power. Then,

Two electric bulbs A and B are designed for the same voltage. Their power rating are Pa and Pb respectively, with Pa>Pb. If they are joined in series across a V-volt supply,

n identical light bulbs, each designed to draw P power from a certain voltage supply, are joined in series across that supply. The total power which they will draw is

A 100W bulb and a 25-W bulb are designed for the same voltage. They have filaments of the same length and material. The ratio of the diameter of the filament 100W bulb to that of the 25W bulb is

An electric bulb rated for 500 watts at 100 volts is used in a circuit having a 200-volt supply. The resistance R that must be put in series with the bulb, so that the bulb draws 500 watts is

Two electric bulbs rate at 25 W, 220 V and 100 W, 220 V are connected in series across a 220-V voltage source. The 25W and 10OW bulbs now draw P25 and P100 powers respectively.

The _____ power is defined as ratio of total work done and the total time taken.