Why Doesn't My Power Calculation Match Real-World Scenarios?

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Aeronautician
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Homework Statement


Hi, guys. I'm in a bit of a quandary. I'm trying to calculate the power a motor should have in order to move a mass a certain distance. My calculation keeps telling me that the horsepower output is much lower than my reference scenario. Here's the situation. I'm trying to figure out how to accelerate a 1633 kg object a distance of 2 m in 1 sec.
m = 1633 kg
d = 2 meters
t = 1 sec

Homework Equations


F=ma
P=F(d/t)

The Attempt at a Solution


Acceleration is thus 2 m/(s^2). According to F=ma, F = 3266 Newtons. Plugging this into P=F(d/t), where d=2m, t=1 sec, Power needed = 6532 Watts or approx 8.8 hp. The problem is in a similar situation, a 215 hp propulsion system is needed to provide the thrust to accelerate and sustain a mass of 95 kg above ground. Where is this discrepancy coming from? My calculations clearly do not correlate with the already established real world scenario. Can I get some direction in this issue?
 
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Aeronautician said:
trying to calculate the power a motor should have
Turning around the preceding responses, your situation is constant power, so not constant acceleration.
The SUVAT equations will therefore not apply. You need to work instead with the more general differential forms.
Work done in time t ##=Pt=\frac 12 mv^2##. Can you solve to find position as a function of time?