Engine Performance(Finding Power)

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To determine the power developed by the car's engine, the user converted the car's acceleration from 101 km/hr to 28.1 m/s and calculated the acceleration as 5.01 m/s². They initially used the formula P = F*v but realized that since power is constant, acceleration must vary. After further consideration, they applied the equation P = W/t, where work is defined as the change in kinetic energy, to find the correct power output. The discussion highlights the importance of understanding the relationship between constant power and varying acceleration in engine performance calculations. The user successfully resolved the problem with the help of forum members.
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Ok, here is the problem:
A car manufactuerer claims that their car can accelerate from rest to 101 km/hr in 5.6 seconds. The car's mass is 840 kg. Assuming that this performance is achieved at constant power, determine the power developed by the car's engine.
Part B) What is the car's speed after 2.8 s?

Ok, so first off i changed the 101km/hr to m/s. So it should be 28.1m/s. Then I used the equation: V=Vo + at to find acceleration and so plugging in 28.1m/s=0 + a(5.6s), a= 5.01m/s^2. So since power = F*v, I plugged in P = 840kg*5.01m/s^2*28.1 = 118256.04 W. This is not right. Since the power is constant, I'm thinking that the acceleration is probably not. So how would I incorporate that into my equation?? Once I get that, I can prolly get part B. Thank's for any help at all!
 
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Check those units are those the Power units?? also think about constant power what does that mean?
 
I ended up getting it. I used the equation P=W/t, where work = change in kinetic energy. Thanks for the help.
 
You know that
F = m \frac {dv}{dt}
What can you conclude if Fv is constant?
 
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