Explain the trade-off between mechanical advantage and speed.

• A. Higher mechanical advantage increases speed.
• B. Trade-off is only about cost.
• C. Higher mechanical advantage increases torque and lowers speed; less advantage increases speed but reduces torque.
• D. Trade-off is not observable.

Answer: (C)

The main idea is that mechanical advantage trades force for motion. When a mechanism provides more output torque (more force at the load), it does so by letting the input move through a smaller distance or by using a larger gear ratio, so the output moves more slowly. Power in roughly equals power out (ignoring losses), so boosting output force means the output speed must drop. Conversely, reducing mechanical advantage lets the output move faster but with less torque. A lever example shows this clearly: pushing on a longer input arm can lift a heavy load, but the load moves a shorter distance each push. In gears, a higher gear ratio increases torque but reduces rotation speed; a lower ratio does the opposite. This is exactly the trade-off described.