Electrical energy can be efficiently converted into mechanical energy through the use of electric motors, which are ubiquitous in various industrial, commercial, and residential applications. This comprehensive guide delves into the measurable quantities, quantifiable data, theoretical explanations, and practical applications of this energy conversion process, providing a valuable resource for physics students and enthusiasts.
Measurable Quantities
Power
 Electrical power is typically measured in Watts (W), which represents the rate of energy transfer.
 Mechanical power can be measured in Watts as well, but it can also be expressed in terms of force and velocity, such as Newtons (N) and meters per second (m/s).
Energy
 Electrical energy is measured in Watthours (Wh), which represents the total amount of energy consumed or generated.
 Mechanical energy can be measured in Joules (J), which is equivalent to 1 Nm (Newtonmeter) and represents the work done or the potential energy stored.
Efficiency
 The efficiency of an electric motor in converting electrical energy to mechanical energy can be measured as a percentage.
 A motor with an efficiency of 80% means that 80% of the electrical energy is converted into mechanical energy, while the remaining 20% is lost as heat.
Quantifiable Data
Electric Motor Efficiency
 Typical efficiency ranges for electric motors:
 Small motors (less than 1 kW): 50% to 70%
 Medium motors (1 kW to 10 kW): 70% to 85%
 Large motors (10 kW to 100 kW): 85% to 90%
 Highefficiency motors: 90% to 95%
Energy Conversion
 Example: A 1 kW electric motor with an efficiency of 80% consumes 1 kWh of electrical energy to produce 0.8 kWh of mechanical energy.
Mechanical Energy Examples
 Kinetic energy of a bowling ball: 50,000 J (50 kJ)
 Potential energy of compressed springs in a dart gun: varies depending on the spring’s properties and compression
Theoretical Explanation
The conversion of electrical energy to mechanical energy in an electric motor involves the interaction of electromagnetic forces. The motor uses electrical currents to generate magnetic fields, which then interact with the motor’s mechanical components to produce motion. The efficiency of this process depends on various factors, such as the motor’s design, materials, and operating conditions.
Physics Formulae
 Electrical Power:

(P_e = V \times I), where (P_e) is the electrical power, (V) is the voltage, and (I) is the current.

Mechanical Power:

(P_m = F \times v), where (P_m) is the mechanical power, (F) is the force, and (v) is the velocity.

Energy Conversion Efficiency:
 (\eta = \frac{P_m}{P_e}), where (\eta) is the efficiency, (P_m) is the mechanical power, and (P_e) is the electrical power.
Numerical Problems
 Efficiency Calculation:

A 5 kW electric motor consumes 6 kWh of electrical energy to produce 4.5 kWh of mechanical energy. What is its efficiency?
 (\eta = \frac{4.5 \text{ kWh}}{6 \text{ kWh}} = 0.75) or 75%

Energy Conversion:
 A 2 kW electric motor with an efficiency of 85% consumes 3 kWh of electrical energy. How much mechanical energy does it produce?
 (P_m = \eta \times P_e = 0.85 \times 3 \text{ kWh} = 2.55 \text{ kWh})
Figures and Data Points
Efficiency vs. Motor Size
 Small motors: 50% to 70% efficient
 Medium motors: 70% to 85% efficient
 Large motors: 85% to 90% efficient
 Highefficiency motors: 90% to 95% efficient
Energy Conversion Example
 Electrical energy: 1 kWh
 Mechanical energy: 0.8 kWh (assuming 80% efficiency)
References
 Our World in Data. (2017). A sense of units and scale for electrical energy production and consumption. Retrieved from https://ourworldindata.org/scaleforelectricity
 ScienceDirect. (n.d.). Measurable Quantity – an overview. Retrieved from https://www.sciencedirect.com/topics/engineering/measurablequantity
 The Physics Classroom. (n.d.). Mechanical Energy. Retrieved from https://www.physicsclassroom.com/class/energy/Lesson1/MechanicalEnergy
 U.S. Department of Energy. (n.d.). Step 2.4 Analyze energy consumption and costs. Retrieved from https://www1.eere.energy.gov/manufacturing/eguide/iso_step_2_4.html
 U.S. Energy Information Administration. (2022). Measuring electricity. Retrieved from https://www.eia.gov/energyexplained/electricity/measuringelectricity.php
Hello, I am Deeksha Dinesh, currently pursuing postgraduation in Physics with a specialization in the field of Astrophysics. I like to deliver concepts in a simpler way for the readers.