Question

the power of engine of car of mass 1200 kg is 25 the minimum time required to reach the velocity of 90 km per hour by the car after starting from rest is

Answer 1

Hi there!


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Given :



Initial velocity (u) = 0



Final velocity (v) = 90 km/h = 25m/s.



Mass of car = 1200 kg.



Power of engine = 25 kW = 25000 W



We know that..



Power = work done / time



Work done = 1 / 2 mv²



=> 1/2 × 1200 × 25 × 25



=> 600 × 625



=> 375000 Joule.



Now,



Time = work done / power



Time = 375000 / 25000



Time = 15 secs.



Hence, the required time is 15 secs.




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Thanks for the question!



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Answer 2

Hi there!

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Given :

Mass of the car = 1200 kg.

Power of the engine = 25 kW

Power of the engine = 25000 W

Initial velocity (u) = 0

Final velocity (v) = 90 km/ h

=> 90 × 5 / 18

=> 25 m/s.

Now,

Work done = 1 / 2 × m v²

Work done = 1 / 2 × 1200 × 25 × 25

Work done = 375000 Joule.

We know that,

Power = work done / time.

Time = work done / power.

Time = 375000 / 25000

Time = 15 seconds.

Hence,

The required time = 15 secs.

___________________________

Thanks for the question !

☺️☺️☺️