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A 1800 kg car increases in velocity from 25m/s to 30m/s. How much work was done on the...

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ssdixon | Student, Undergraduate | Salutatorian

Posted March 26, 2012 at 11:07 AM via web

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A 1800 kg car increases in velocity from 25m/s to 30m/s. How much work was done on the car to increase it to its final velocity.

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justaguide | College Teacher | (Level 2) Distinguished Educator

Posted March 26, 2012 at 11:13 AM (Answer #1)

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The velocity of a 1800 kg car increases from 25 m/s to 30 m/s. The kinetic energy of an object with mass m and traveling with a velocity v is given by (1/2)*m*v^2.

The initial velocity of the car was 25 m/s. This gives the initial kinetic energy as (1/2)*1800*25^2 = 562500 J

The final velocity of the car is 30 m/s. This gives the final kinetic energy of the car as (1/2)*1800*30^2 = 810000 J

As the increase in energy is 810000 - 562500 = 247500 J that is the work done on the car.

The work done on the car with a mass 1800 kg to increase the speed form 25 m/s to 30 m/s is 247500 J

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pranitingale | Student, Grade 9 | Valedictorian

Posted March 26, 2012 at 5:44 PM (Answer #2)

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TOTAL WORK DONE = CHANGE IN KINETIC ENERGY

          WORK DONE = FINAL KINETIC ENERGY - INITIAL KINETIC ENERGY

                          W = (1/2)mv^2 - (1/2)mu^2

                          W = (1/2)*1800*30^2 - (1/2)*1800*25^2

                          W = 810000 - 562500

                          W = 247500 J

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