18 A car of mass 1800 kg accelerates along a horizontal road so that its speed increases from 20ms^-1 to 25ms^-1 in a time of 5.4s. What is the average useful power output of the car's engine? A 4.2 kW B 38KW C 120kW D 1100 kW

Question

Answer 1

To find the average useful power output of the car's engine, we can use the formula for power:

where

is power,

is work done, and

is time.First, we need to calculate the work done by the car. The work done is equal to the change in kinetic energy of the car:

where

is the mass of the car,

is the final velocity, and

is the initial velocity.Given:- Mass of the car,

- Initial velocity,

- Final velocity,

- Time,

Now, calculate the change in kinetic energy:

Next, calculate the average power output:

Therefore, the average useful power output of the car's engine is approximately 38 kW.So, the correct answer is:B. 38 kW

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