At any instant of time $t$, the displacement of a particle is given by $x = 2t - 1$ ($SI$ units) under the influence of a force of $5 \,N$. The value of instantaneous power is (in $SI$ units):

$A$ lift raises $50$ passengers, each having an average weight of $600 \,N$, to a height of $100 \,m$ at a constant speed in time $t$. If the average power of $15 \,kW$ is required by the lift, then the value of $t$ in seconds is:

$A$ machine gun fires $300$ bullets per minute, each with a velocity of $500 \,ms^{-1}$. If the mass of each bullet is $4 \,g$, the power of the machine gun is: (in $\,kW$)

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 $g = 10 \ m/s^2$.)

$A$ motor pump lifts $6$ tonnes of water from a well of depth $25 \ m$ to the first floor of height $35 \ m$ from the ground floor in $20$ minutes. The power of the pump (in $kW$) is: $[g=10 \ ms^{-2}]$

$A$ force of $(2\hat i + 3\hat j + 4\hat k) \text{ N}$ acts on a body for $4 \text{ s}$ and produces a displacement of $(3\hat i + 4\hat j + 5\hat k) \text{ m}$. The power used is ............. $\text{W}$. (in $.5$)