V K Sally and R Goel Solutions for Chapter: Work and Energy, Exercise 14: EXERCISE

 In terms of mass, length and time, Watt is represented by

An electric heater is rated $1500 \text{W}$. The energy used by it in $10$ hours is :

The energy consumed (in $\mathrm{KWh}$) by four devices of $500 \mathrm{W}$ each in $10$ hours is:

A machine does a work of $1960 \text{J}$ in $24 \mathrm{s}$. The power of the machine is :

An engine does a work of $600 \text{J}$ in $1$ minute. The power of engine in kilowatts is :

A boy of mass $50 \text{Kg}$, runs up a flight of $120$ stairs, each measuring $25 \text{cm}$ in one minute and $40$ seconds. If $\mathrm{g}=10 \mathrm{m}/{\mathrm{s}}^2$ the power of the boy is: 

A motor pump of power $400 \text{W}$ operates for $2$ minutes and $40 \text{s}$ and in doing so raises $200 \mathrm{k}\text{g}$ of water through a vertical height $h$. If $\mathrm{g}=10 \mathrm{m}/{\mathrm{s}}^{\mathrm{2}}$, the magnitude of $\text{'}h\text{'}$ is:

When the time to complete work increases, its: