Final answer:
A mechanical advantage lower than 1 does not make a machine useless; it depends on the machine's intended purpose. For instance, a bicycle has a mechanical advantage lower than 1 because it is designed to increase speed, not amplify force.
Step-by-step explanation:
No, a mechanical advantage lower than 1 does not necessarily make a machine useless. The concept of mechanical advantage (MA) is central to understanding how machines work. It is the ratio of the output force produced by the machine to the input force that is applied. A mechanical advantage greater than 1 means that the machine amplifies the input force, which is useful in cases like levers where a smaller force is needed to lift heavy loads.
However, not all machines are designed to amplify force; some are designed to increase speed or distance traveled. In the case of a bicycle, the mechanical advantage can be lower than 1 because the aim is to convert a greater input force into higher speeds, which involves increasing the distance over which the force is applied. This is why we can travel faster and cover more ground on a bicycle than we can walking, even though the input force (from our legs) is greater when cycling.
The functionality of a machine has to be assessed in the context of its intended purpose. So, while the mechanical advantage provides insight into how a machine multiplies force, it does not define the usefulness of a machine. The efficiency of a machine, which is the ratio of output work to input work, is also an important factor to consider.