Question

the speed of motorcycle changes from 5m/s to 20m/s the ratio of initial and final kinetic energy is​

Answer 1

initial will be 1/2*m*u2

final will be 1/2*m*v2

ratio will be u2:v2

ie. 25:400

1:16

Answer 2

Given: The speed of motorcycle changes from 5 m/s to 20 m/s.

To find: Ratio of initial and final kinetic energy

Explanation: Let mass of the motorcycle be m.

Initial velocity(u)= 5 m/s

The formula for initial kinetic energy is as follows:

=$\frac{1}{2} m {u}^{2}$

=$\frac{1}{2} m \times 25$

=$12.5m$

Final velocity(v)= 20 m/s

Final kinetic energy is equal to:

=$\frac{1}{2} m {v}^{2}$

=$\frac{1}{2} m \times 400$

=200m

The ratio of initial and final kinetic energy is:

=$\frac{12.5m}{200m}$

=$\frac{1}{16}$

=1:16

Therefore, the ratio of initial and final kinetic energy is 1:16.