Question

A Porsche 944 Turbo has a rated engine power of 217 hp. 30% of the power is lost in the drive train, and 70% reaches the wheels. The total mass of the car and driver is 1420 kg, and two-thirds of the weight is over the drive wheels.

(a) What is the maximum acceleration of the Porsche on a concrete surface where

Answer 1

P = FV

P= 0.70 Pmax

Fmax V = 0.70 Pmax

V = 0.70 Pmax / Fmax

f = mus (2/3)mg

f = Fmax

F=ma (and Fmax)

ma = mus (2/3) mg

amax= mus (2/3) g

amax =  0.92 * (2/3) * 9.81

= 6.0 m/s2

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V = 0.70 Pmax / Fmax

V = 0.70 Pmax/ mamax

V = 0.70 x 217 x 746/ (1420 x 6.0)

V=13.3 m/s

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t = V/a= 13.3 /6.0

= 2.22 s