Question

A body of mass 1kg falling from height 30m if it reaches the ground with speed 20m/s then work done by the air resistance is
a)-100 b)-200 c) -300 d)-400

Answer 1

Answer:

option A is correct

i. e

-100

Answer 2

Answer:-100

Explanation:apply work energy theorem

Wall=dela k

Wgravity+Wair=1/2m(20^2-0)

mgh+wair=1/2 x 400=200

Wair=200-10 x30=-100