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want a quick help

If a car engine makes a car of mass 1500 kg move with a constant velocity of 5m/s and the force of friction is 1000 N then what is the power of the engine?

a. 5kW




if you get answer other than 5kW then please mention the solution also. Require the solution in maximum 3 hrs. if you can. thank you.

Note by Ansh Bhatt
1 year, 6 months ago

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  • Instantaneous power = \(F*v = 1000*5 = 5kW\)(at start)

  • Average power = \(\dfrac{Work \quad done}{time}\)

W = Force* displacement

Acceleration = F/m = 2/3 \(m/s^2\)

Now using third equation of motion (final velocity = 0)

\(v^2 = u^2 + 2as\)

\(s = \frac{u^2}{2a} = \frac{75}{4}\) (body is decelerating)

By first equation of motion

\(t = u/a = \frac{15}{2} s\)

\(P_{avg} = \dfrac{1000*75/4}{15/2} = 2.5kW\) Krishna Sharma · 1 year, 6 months ago

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@Krishna Sharma Thank you. @Krishna Sharma Ansh Bhatt · 1 year, 6 months ago

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