Question

please solve this..
actually I'm not getting the correct answer (눈‸눈)​

Answer 1

Question:-

It is well known that a raindrop falls under the influence of the gravitational force and the opposing resistive force. The latter is known to be proportional to the speed of the drop but is otherwise undetermined. Consider a drop of mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 ms ¹. What is the work done by the unknown resistive force?

Answer:-

$\textbf{Given:-}$

$\sf \colorbox{god} {Mass of rain drop,}m = 1g = 0.001kg$

Height from where the rain drop falls, h = 1 km = 100 m

$\sf \colorbox{god} {Speed of rain drop,}v = 50 {ms}^{ - 1}$

Consider the work done by the unknown resistive force be W, then according to work-energy theorem

we have,

$⇒W +W ' = \sf \colorbox{god} {} \frac{1}{2} {mv}^{2} - \frac{1}{2} {mu}^{2}$

$⇒W' = \sf \colorbox{god} {} \frac{1}{2} {mv}^{2} - \frac{1}{2} {mu}^{2} - W$

$= \frac{1}{2} \times 0.001 \times {50}^{2} - \frac{1}{2} \times 0.001 \times {0}^{2} - 9.8$

$= 1.25 - 0 - 9.8 = - 8.55J$

$\\ \\ \\ \\ \sf \colorbox{lightgreen} {\red★ANSWER ᵇʸɴᴀᴡᴀʙ⌨}$