$A$ $2\,kg$ chain is in the form of a heap. Its length is $2\,m$. Its one end is being pulled at a constant speed of $2\,m/s$ horizontally. The power delivered to the chain is (in $W$).

$A$ conveyor belt is moving with a constant velocity $V$. Sand is being dropped on the belt at the rate of $M \text{ kg/s}$. The force necessary to keep the belt moving with a constant velocity $V \text{ m/s}$ will be

$A$ heap of rope with mass density $\lambda$ (per unit length) lies on a table. You grab one end and pull horizontally with constant speed $v$,as shown in the figure. (Assume that the rope has no friction with itself in the heap.) The force that you must apply to maintain the constant speed $v$ is

$A$ $5000\, kg$ rocket is set for vertical firing. The exhaust speed is $800\, m/s$. To give an initial upward acceleration of $20\, m/s^2$,the amount of gas ejected per second to supply the needed thrust will be ........... $kg/s$ $(g = 10\, m/s^2)$. (in $.5$)

$A$ $6000 \,kg$ rocket is set for firing. If the exhaust speed is $1000 \,m/s$,how much gas must be ejected each second to supply the thrust needed to overcome the weight of the rocket?

The motion of a rocket in an upward direction with high speed is based on the principle of conservation of: