work done

Work done = (1/2)mv² - 0 = (1/2)x 10 x 100 - 0 = 500 J

 

If the object falls freely under the influence of gravity, let v' is the velocity attained by the object at height of 10 m.

 

v'² = u² + 2 gh = 0 + 2 x 10 x 10 = 200 units

 

Now in this case work done = (1/2)mv'² - 0 = (1/2)x10x200 - 0 = 1000J

 

So the work done by the push of the air on the object = 1000 - 500 = 500J