NEET Solved Paper 2017 Question 40
Question: Consider a drop of rain water having mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 m/s. Take g constant with a value $ 10,m/s^{2}. $ The work done by the (i) gravitational force and the (ii) resistive force of air is
Options:
A) (i) 10 J (ii) -8.75 J
B) (i) -10 J (ii) -8.25 J
C) (i) 1.25 J (ii) -8.25 J
D) (i) 100 J (ii) 8.75 J
Show Answer
Answer:
Correct Answer: A
Solution:
$ w _{g}w _{a}=K _{f}-K _{i} $
$ mgh+w _{a}=\frac{1}{2}mv^{2}-0 $ $ {10^{-3}}\times 10\times 10^{3}+w _{a}=\frac{1}{2}\times {10^{-3}}\times {{(50)}^{2}} $ $ w _{a}=-8.75,J $
i.e. work done due to air resistance and work done due to gravity = 10 J
