Question

a car is running at a speed of 15 km per hour while another similar car is moving at a speed of 30 km per hour find the ratio of their Kinetic energies

Answer 1

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Answer 2

Answer:

Ratio of their Kinetic energies =1:4

Explanation:

Since we know that the K.E of a body = $\dfrac{mv^{2}}{2}$

Velocity of first car is 15 km per hour=4.167 m/s.

So,kinetic energy of first car is

$K.E_{1} =\dfrac{m(4.167)^{2} }{2}=m8.68\ Joules$

Velocity of Second car is 30 km per hour=8.34 m/s.

So,kinetic energy of Second car is

$K.E_{2} =\dfrac{m(8.34)^{2} }{2}=m34.78\ Joules$

Ratio of their Kinetic energies=$\dfrac{8.68}{34.78}=0.25:1$

Ratio of their Kinetic energies =1:4