Question

A car with a mass of 1710 kg kg starts from rest and accelerates to a speed of 13.8 m/s in 13.5 s. Assume that the force of resistance remains constant at 367.1 N during this time.
What is the average power developed by the car’s engine?
Answer in units of W

Answer 1

Answer:

Average Power = 14599.24 W

Explanation:

We know that :

$power = \frac{work \: done}{time}$

$work \: done \: = force \times displacement \: \cos( \alpha )$

Acceleration of car (a) = v - u / t

= 13. 8 - 0 / 13.5

= 1.02 m / sec ^2

Displacement (s) = v^2 / 2a

= 13.8 * 13.8 / 2.04

= 93.35 m

Now,

Resultant force = F (Car) - F (Resistance) = m * a

Force (Car) = m * a + Force (Resistance)

Force (Car) = 1744.2 + 367.1 = 2111.3 N

Work done by Car = Force (Car) * Displacement

= 2111.3 * 93.35 * Cos 0°

= 197089.85 J

Average Power = Work Done / time

= 197089.85 J / 13.5 sec

= 14599.24 W