Friction between moving parts primarily results in what two effects?

• A. Loss of productive power and heat
• B. Increased speed and noise
• C. Decreased torque and vibration
• D. Reduced friction and cooling

Answer: (A)

Friction between moving parts converts part of the input mechanical energy into heat. That energy loss shows up as a drop in productive power (the system runs less efficiently and delivers less useful output for the same input) and an increase in temperature as the components and lubricant heat up. Over time, this heating can lead to wear or reliability issues if not managed with proper lubrication and clearances.

The other choices don’t fit because friction resists motion rather than speed up, so it wouldn’t increase speed. Friction also doesn’t inherently reduce friction or cooling; it is the energy-dissipating source that causes heating, while lubrication aims to reduce friction and manage heat.