Question

the kinetic energy of an object of mass, m moving with a velocity city of 5ms-1 is 25 J. what will be its kinetic energy if its velocity is doubled?

(Answers)

Expression for kinetic energy 

Ek= ½ mv2 

m = Mass of object 

v = Velocity of the object in ms−1 

Given that kinetic energy, Ek=25J 

(i) If the velocity of an object is doubled, then v = 5 × 2 = 10 ms−1 . Therefore, its kinetic energy becomes 4 times its original value, because it is proportional to the square of the velocity. 

Hence, kinetic energy = 25 × 4 = 100 J. 

(ii) If velocity is increased three times, then its kinetic energy becomes 9 times its original value, because it is proportional to the square of the velocity. Hence, kinetic energy = 25 × 9 = 225 J.80

Answer 1

first find mass of the object using 1/2 mv^2
then substitute mass to find the new kinetic energy
you get mass as 10
so new kinetic energy is 1/2 ×100×10
which is 500