A motor is rated to deliver (output) 2.5 hp at 120 VDC. If the motor runs on 120 V and is 75% efficient, how many watts does it draw from the power line (input) ? (input power is always greater than output power, and remember to use a horse power conversion: 1hp = 746 (watts) (a) 3.33 W (b) 1399 W (c) 1679 w (d) 2072 W (e) 2487 W

(e) 2487 W

Explanation:

Given data

voltage = 120 V

power = 2.5 hp

efficiency = 75%

To find out

watts draw from the power line

solution

we calculate efficiency by given formula

efficiency = (output / input) * 100 ... 1

we know our output is 2.5 hp = 2.5 * 746 = 1865 W

and efficiency is 75% = 0.75

put these value in equation 1 and find out input power

power = (1865 / 0.75)

power = 2486.66 W

so our answer is (e) 2487 W