Question Text
Question 1 :
Assertion: kilowatt hour is the unit of electric power.
Reason: watt hour has units of energy.
Question 2 :
If an electric iron of 1200 W is used for 30 minutes everyday, find electricenergy consumed in the month of April.<br><br>
Question 3 :
An engine develops $10kW$ of power. How muchtime will it take to lift a mass of $200\ kg$ to aheight of $40 \m$. [$g= 10ms^{-2}$]
Question 4 :
A boy, whose weight is $600 N$ runs up a flight of stairs, $10 m$ high, in a time of $12 s$. What is the average power developed by boy in $watts$?
Question 5 :
The velocity of a train is increased from $10\ ms^{-1}$to $25 \ ms^{-1}$ in $2$ minutes due to the application of some force by its engine developing an average power of $525\ kW$. Neglecting frictional forces, the mass of the train must be
Question 6 :
A pump motor is used to deliver water at a certain rate from a given pipe. To obtain thrice as much water from the same pipe in the same time, power of the motor has to be increased to:
Question 7 :
An electric motor of power $100W$ is used to drive the stirrer in a water bath. If $50$% of the energy supplied to the motor is spent in stirring the water, find the work done on water in one minute.
Question 8 :
When we pay for our electricity bill, we are paying for the ____________.
Question 9 :
A pump is used to lift $500kg$ of water from a depth of $80m$ in $10s$. Calculate the power at which the pump works. (Take $g=10\ ms^{-2}$)<br/>
Question 10 :
If a force F is applied on a body and it moveswith a velocity V, the power will be