Final answer:
Efficiency is the ratio of output work to input work in a machine. Wheelbarrows are compound machines with multiple simple machines. Screws and wedges are modified versions of the inclined plane.
Explanation:
Efficiency in a machine is the ratio of output work to input work, representing how well a machine converts input work into useful output work. For example, if a machine has an efficiency of 80%, it means 80% of the input work is converted into useful output work.
A wheelbarrow is a compound machine because it consists of multiple simple machines working together. It typically involves a wheel and axle as well as an inclined plane to help with lifting and moving heavy loads.
The screw and wedge are both modifications of the inclined plane. A screw is a spiral inclined plane wrapped around a cylinder, while a wedge is formed by two back-to-back inclined planes that meet to form a sharp edge, such as in knives or axe heads.
Learn more about Simple machines here:
https://brainly.com/question/19336520
