Question

In an electric vehicle, each wheel is powered by its own motor. The vehicle weight is 4,000 lbs. By regenerative braking, its speed is decreased linearly from 60 mph to 30 mph in 10 seconds. Calculate the theoretical maximum energy in kWh that can be recovered during this interval. Ignore all losses.

Answer 1

the theoretical maximum energy in kWh that can be recovered during this interval is 0.136 kWh

Step-by-step explanation:

Given that;

weight of vehicle = 4000 lbs

we know that 1 kg = 2.20462

so

m = 4000 / 2.20462 = 1814.37 kg

Initial velocity
`V_(i)` = 60 mph = 26.8224 m/s

Final velocity
`V_(f)` = 30 mph = 13.4112 m/s

now we determine change in kinetic energy

Δk =
`(1)/(2)`m(
`V_(i)`² -
`V_(f)`² )

we substitute

Δk =
`(1)/(2)`×1814.37( (26.8224)² - (13.4112)² )

Δk =
`(1)/(2)` × 1814.37 × 539.5808

Δk = 489500 Joules

we know that; 1 kilowatt hour = 3.6 × 10⁶ Joule

so

Δk = 489500 / 3.6 × 10⁶

Δk = 0.13597 ≈ 0.136 kWh

Therefore, the theoretical maximum energy in kWh that can be recovered during this interval is 0.136 kWh