A 120-V motor has mechanical power output of 3.00 hp. It is 94.0% efficient in converting power that it takes in by electrical transmission into mechanical power.
(a) Find the current in the motor.
I got the same answers,17.5 A, whether I used round conversion or whole decimal answers conversion from hp to watts but it keeps saying my answer is differ by 10%
0.94 V I = 746*3.0 = 2238 W
I = 2238/[0.94*120] = 19.8 A
To find the current in the motor, you will need to use the given information about the mechanical power output and the efficiency.
(a) First, convert the mechanical power output from horsepower to watts.
1 horsepower (hp) is equal to 746 watts. Therefore, the mechanical power output is:
Pmech = 3.00 hp * 746 W/hp = 2238 W
(b) Next, use the efficiency to find the electrical power input.
Efficiency = (Pmech / Pin) * 100
Rearranging the equation, we have:
Pin = (Pmech / Efficiency) * 100
Substituting the given values, we get:
Pin = (2238 W / 94.0%) * 100 = 2380.85 W
(c) Lastly, use the electrical power input and the voltage to find the current using Ohm's Law, which states:
Power (P) = Voltage (V) * Current (I)
Rearranging the equation, we have:
Current (I) = Power (P) / Voltage (V)
Substituting the given values, we get:
I = 2380.85 W / 120 V
I ≈ 19.84 A
So, the current in the motor is approximately 19.84 A.