🔍 Key Concepts

• Power = Speed × Torque relationship in rotating machinery • What a reduction gear does to RPM (revolutions per minute) and torque • Conservation of power in an ideal gear system (ignoring losses)

💭 Think About

• If engine speed (RPM) goes down through a reduction gear but the power transmitted stays about the same, what must happen to torque? • Think about why ship propellers usually turn slower than the engine but can still push a heavy vessel—what does that say about torque at the shaft? • Compare this to riding a bicycle in low gear going up a hill: your pedal speed versus the force at the wheel.

✅ Before You Answer

• Be clear on the difference between speed (RPM) and torque (twisting force). • Remember that in an ideal gear system, input power ≈ output power, so changes in speed must be balanced by opposite changes in torque. • Eliminate any choice that would violate conservation of power when speed is reduced but power is roughly unchanged.