Which machine is the LEAST efficient? A pulley with 85\% efficiency A wheelbarrow with \( 75 \% \) efficiency A screw driver with \( 80 \% \) efficiency

In this case, the wheelbarrow is the least efficient machine, operating at \( 75 \% \) efficiency. This means that it loses a larger portion of energy compared to the other options. While all machines have some degree of inefficiency, the design of a wheelbarrow involves overcoming significant friction when transporting heavy loads, which can impact its overall effectiveness. To enhance efficiency when using a wheelbarrow, make sure to distribute the load evenly and maintain the wheel's condition. Common mistakes include overloading it beyond its capacity, which can lead to stalling or damage. If you can, choose paths with less resistance or use smooth surfaces to make your work easier and more effective!