2. A 1.00 x 103 kg sports car accelerates from rest to 25.0 m/s in 7.50 s. What is the

average power output of automobile engine?

a. 20.8 kW

b. 30.3 kW

C. 41.7 kW

C = 41.7kW

Explanation:

Data;

Mass (M) = 1x10³kg

Initial velocity (u) = 0m/s

Final velocity (v) = 25m/s

Time (t) = 7.5s

Power = Work / time

Work = force * distance

acceleration = average velocity / time

Acceleration = (25 - 0) / 7.5 = 3.3m/s²

Power = force * velocity (speed)

Average velocity = (25 - 0) / 2 = 12.5m/s

Force = mass * acceleration = 1x10³ * 3.3 = 3333.33N

Power = force * velocity

Power = 3333.33 * 12.5 / 41666.67W

C. 41.7 kW

Explanation:

car's acceleration is the velocity difference over time: a = (v1 - v0) / t = (25 - 0) / 7.5 = 3.3 m/s^2

The avg. power P = F * v

The avg. speed is thus v = (v0 + v1) / 2 = (0 + 25) / 2 = 12.5 m/s

F = m * a = 1*10^3 * 3.3 = 3,333 N

P = 3,333 * 12.5 = 41,667 W = 41.7 kW