Question

A body of mass 1kg is thrown upwards with a velocity of 20m/s.It momentarily comes to rest
After attaining a height of 18m.How much energy is lost due to air friction..?


Please send me the Deriviation.....

Answer 1

since kinetic energy =1/2 mv2
so K.E = 1/2 (1)(20)^2
= 200J
again P.E = mgh
=1×10×18
=180J
Therefore Energy lost due to air friction is =K.E-P.E
=(200-180)J
= 20J