a 4.5kw electric motor is 90% efficient.how much energy it use in 20 seconds.
E=Pt/η=4500•20/0.9=100000 J =0.1 MJ
4.5kW = 90%
5.0kW = 100%
W= 5000W x 20
= 100000J @ 100kJ
12 minutes
13 minutes
100KJ
90kj
To calculate the energy used by a 4.5 kW electric motor in 20 seconds, you need to take into account its efficiency.
First, let's convert the power rating to watts:
4.5 kW * 1000 = 4500 watts
Now, as the motor is 90% efficient, we can find the actual power consumed by multiplying the power rating by the efficiency:
4500 watts * 0.90 = 4050 watts
To calculate energy, we use the equation:
Energy = Power * Time
Now, plug in the values:
Energy = 4050 watts * 20 seconds
Multiplying the power by the time:
Energy = 81000 watt-seconds (or joules)
So, the 4.5 kW electric motor would use 81,000 joules of energy in 20 seconds.