Question

Calculate the decrease in the kinetic energy of a moving body if it's velocity reduces to one third of the initial velocity


Guys..its way too urgent...plz answer!!!

Answer 1

If initial​ kinetic energy of the body is mv²/2 and its velocity decreases to one third.
Therefore the new kinetic energy, is

m(v/3)²/2 =(1/9)mv²/2

the decrease in kinetic energy = mv²/2-(1/9)mv²/2 = (8/9)mv²/2

percentage decrease =
{ {(8/9)mv²/2}/mv²/2}×100
8×100/9 =88.89%