SOLUTION: A 52 kg student traveling in a car with a constant velocity has a kinetic energy of 1.6* 10^4 J. What is the speedometer reading of the car in km/h?

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Question 1205987: A 52 kg student traveling in a car with a constant velocity has a kinetic energy of 1.6* 10^4 J. What is the speedometer reading of the car in km/h?
Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

given:
m=52kg
K=1.6%2A10%5E4%2AJ


the kinetic energy is
K=%281%2F2%29mv%5E2 where m is the mass and v is the velocity

1.6%2A10%5E4%2AJ=%281%2F2%29%2A52%2Av%5E2

since 1J=1km%5E2%2Fs%5E2

%281.6%2A10%5E4%2A%28km%5E2%2Fs%5E2%29%29%2F%2852%2F2%29=v%5E2

v%5E2=615.3846153846155%28km%5E2%2Fs%5E2%29

v=sqrt%28615.3846153846155%28km%5E2%2Fs%5E2%29%29

v=24.81%28km%2Fs%29


Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
.

Use the formula  %28mv%5E2%29%2F2 = E  for kinetic energy E, known from any Physics textbook.


Substitute given values for the mass m and for kinetic energy E and find v from equation

    %2852%2Av%5E2%29%2F2 = 1.6%2A10%5E4.

Happy calculations  ( ! )

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