What would be an example of a simple machine?

A pulley is a classic example of a simple machine, which is a device that makes work easier by allowing a person to apply force in a more efficient way. Simple machines reduce the amount of effort needed to lift or move a load by changing the direction of the force applied or by distributing it over a greater distance.

In the case of a pulley, it consists of a wheel on an axle or shaft that is designed to support movement and change of direction of force applied to a rope or cable. When a load is attached to one end of the rope and the other end is pulled down, it allows the user to lift heavy weights with significantly less effort than attempting to lift them directly.

The other options listed do not fit into the category of simple machines. A robot, engine, and computer are all complex systems made of multiple components and mechanisms that work together, rather than simple machines that demonstrate fundamental mechanical principles.