Question

A raindrop of mass 2.52 × 10-5 kg falls vertically at constant speed under the influence of gravity and air resistance. Model the drop as a particle.
(a) As it falls 100 m, what is the work done on the raindrop by the gravitational force?J
(b) What is the work done on the raindrop by air resistance?J

Answer 1

Answer:

0.0247212 Joules

-0.0247212 Joules

Explanation:

Potential energy

$PE=mgh\\\Rightarrow PE=2.52\times 10^{-5}\times 9.81\times 100\\\Rightarrow PE=0.0247212\ Joules$

a) The work done by the gravitational force is given by the potential energy that the body has at the start of the fall.

Work done is considered as positive if the force which is being applied is in the direction of motion.

Hence, the work done on the raindrop by the gravitational force is 0.0247212 Joules

b) As the drop is falling the air resistance provides an opposite force this means the sign of the work done will be negative.

So, the work done on the raindrop by air resistance is -0.0247212 Joules