An engine develops $20 kW$ of power. How much time will it take to lift a mass of $200 kg$ to a height of $40 m$ (in $s$)? $(g=10 m s^{-2})$

Two bodies of mass $m_1$ and $m_2$ $(m_2 > m_1)$ are connected by a light inextensible string which passes through a smooth fixed pulley. The instantaneous power delivered by an external agent to pull $m_1$ with constant velocity $v$ is

$A$ block of mass $50 \,kg$ is pulled with a constant speed of $4 \,ms^{-1}$ across a horizontal floor by an applied force of $500 \,N$ directed $30^{\circ}$ above the horizontal. The rate at which the force does work on the block in watt is

Air strikes the blades of a windmill with a speed of $v$. The power generated is proportional to which of the following?

Water falls from a dam at a height of $550 \ m$ onto a turbine at a height of $50 \ m$ at a rate of $2000 \ kg$ per second. If the efficiency of the turbine is $80\%$,the power generated is ............. $MW$.

An engine pumps $100 \ kg$ of water to a height of $10 \ m$ in $5 \ s$. If the efficiency of the engine is $60\%$,the power of the engine is........$kW$. (Take $g = 10 \ m/s^2$.)