$A$ machine with efficiency $2/3$ uses $12 \text{ J}$ of energy to lift a $2 \text{ kg}$ block to a certain height. If the block is allowed to fall freely from that height,what is its velocity when it reaches the ground?

$A$ machine which is $75\%$ efficient, uses $12 \, J$ of energy in lifting up a $1 \, kg$ mass through a certain distance. The mass is then allowed to fall through that distance. The velocity at the end of its fall is (in $m \, s^{-1}$):

$A$ particle of mass $m$ is dropped from a height $h$ above the ground. At the same time,another particle of the same mass is thrown vertically upwards from the ground with a speed of $\sqrt{2gh}$. If they collide head-on completely inelastically,the time taken for the combined mass to reach the ground,in units of $\sqrt{\frac{h}{g}}$,is

Which of the following is generally true when two particles collide?

$A$ block of mass $5 \,kg$ is moved by a distance of $10 \,m$ on a surface with a coefficient of friction $\mu = 0.2$ by applying a force of $25 \,N$. The kinetic energy gained by the block is ...... $J$. (Take $g = 10 \,m/s^2$)

$A$ body is moved from rest along a straight line by a machine delivering constant power. The ratio of displacement and velocity $(s/v)$ varies with time $t$ as :