Given : Initial velocity =v; Final velocity =‌

v

3

Initial kinetic energy k1=‌

1

2

×m×v2
Final kinetic energy k2=‌

1

2

×m×(‌

v

3

)2
=‌

1

9

×‌

1

2

mv2
Change in kinetic energy
‌=‌

1

2

mv2−‌

1

9

×‌

1

2

mv2
‌=‌

1

2

mv2(1−‌

1

9

)=‌

8

9

×(‌

1

2

mv2)
=‌

8

9

×‌ Initial kinetic energy. ‌