Question

e) 'K' is the initial kinetic energy of a body. If its velocity becomes half, then its kinetic energy will become: i. K/4
ii. K/2
iii. 2 K
iv. 4K​

Answer 1

Given: initial kinetic energy = K

             initial velocity = v

             new velocity = v' = 1/2v

To Find: new Kinetic energy = K'

Solution:

Formula used:

Kinetic energy = 1/2mv²

K ∝ v² ( kinetic energy is directly proportional to v²)

Let's find out K/K'

K/K' = v²/v'²

K' = v'²/v² × K

K' = (1/2v)²/v² × K

K' = 1/4v²/v² × K

K' = 1/4K

K' = K/4

∴the new kinetic energy will become K/4 .