Question

Two cars having the same mass of 150kg. The first car changes its velocity from 5m/s to 10m/s and the Second car changes it’s velocity from 10m/s to 15m/s. Find out which car has more kinetic energy.

Answer 1

for car (1)

mass =150kg

k(e)=1/2mv^2

= 1/2*150*10^2-5^2

=1/2*150*75

=5625J

For car(2)

mass=150kg

k(e)=1/2*150*(15^2-10^2)

=1/2*150*125

=9375J

hence car two has more kinetic energy (9375J)

Answer 2

mass = 150 kg

velocity = 5m/s

kinetic energy = 1/2 mv²

= 1/2 *150*25 = 1875j

velocity = 10m/s

kinetic energy = 1/2 mv² = 1/2*150*100

=>7500

car changes his velocity = 7500 - 1875 =>5625

second

kinetic energy =1/2 mv² - 1/2mv²

= 1/2*150*225 - 1/2*150*100

= 16875 - 7500 = 9375

so,

second car has more kinetic energy