1.1.15 Improving Efficiency

• The efficiency of a device can be improved by reducing wasted energy transfers.
• Machines waste energy due to friction between their moving parts, air resistance, electrical resistance, and sound.
• Friction can be reduced by adding bearings to prevent components from directly rubbing together and lubricating parts.
• Air resistance causes a frictional force between the moving object and the air that opposes its motion, resulting in unwanted energy transfers by heating to the object and the surroundings.
• Air resistance can be reduced by streamlining the shapes of moving objects and adopting a more streamlined posture.
• Many factors such as posture, clothes, and bicycle shape must be considered when trying to reduce air resistance.
• Sound is often created by moving parts of machinery, resulting in unwanted energy transfers by heating to the surroundings as sound waves cause the particles in the air and nearby objects to vibrate.
• Sound can be reduced by tightening loose parts to reduce vibration and lubricating parts.