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Question
A car is moving with a speed of 15 km h-1 and another identical car is moving with a speed of 30 km h-1. Compare their kinetic energy.
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Solution
Two identical cars mean, they have equal mass
K.E = 1/2 mv2
Let m be the mass of each car
Kinetic energy of car A = `1/2` m × `(15)^2` = `225/2` m
= 112.5 m J
Kinetic energy of car B = 1/2 M (30)2
=450 M J
`(K.E. of A) /(K.E. of B)` = `(225 m )/(2 × 450 m )` = `1/4` = 1 : 4
K.E. of car B is 4 times K.E. of car A.
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