The main shaft transmits what kind of energy from the hub to the gearbox?

• A. Electrical
• B. Thermal
• C. Magnetic
• D. Mechanical

Answer: (D)

The main idea here is mechanical power transmission. The main shaft’s job is to carry rotational motion and torque from the hub to the gearbox, effectively transferring mechanical energy as the system rotates. This energy is described by power = torque × angular velocity, so the shaft is all about conveying that rotational work.

Electrical energy would be carried by conductors, not a shaft. Thermal energy refers to heat transfer, which is not the primary purpose of a shaft in transmitting power. Magnetic energy involves magnetic fields and couplings, not the direct transfer of torque and speed through a shaft. So the shaft is best described as transmitting mechanical energy.