A Porsche 944 Turbo has a rated engine power of 217 hp. 30% of the power is lost

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 1530 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 s=1.00?

Express your answer with the appropriate units.

b)

If the Porsche accelerates at amax, what is its speed when it reaches maximum power output?

Express your answer with the appropriate units.

c)

How long does it take the Porsche to reach the maximum power output?

Express your answer with the appropriate units.

Explanation / Answer

1 hp = 746 watts
217 hp = 161,882 watts
70% = 113,317.4 watts
a)
Weight = 1530 * 9.8
Friction force = s * (weight over drive wheels)
Friction force = 1 * * 1530 * 9.8 = 9996 N

If the drive wheels exert a force that is greater than 9996 N, the tires will spin. So, the maximum force that the wheels can exert = 9996 N

Maximum force = mass * maximum acceleration
Maximum acceleration = 9996 ÷ 1530 = 6.5333 m/s^2
b)
Power = Work ÷ time
Work = Force * distance
Power = Force * distance ÷ time
Speed = distance ÷ time

Power = Force * speed
113,317.4 = 9996 * speed
Speed = 11.33 m/s
c)
Acceleration max = speed ÷ time
6.5333 = 11.33 ÷ time
Time = 1.7342 seconds

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.