Final answer:
Mary's machine makes her work easier by allowing her to apply force over a greater distance, which reduces the force needed at any moment while keeping the total work done constant, thanks to the mechanical advantage of simple machines.
Step-by-step explanation:
Mary is using a machine that requires her to increase the force she is applying over a greater distance. Although this might seem more challenging, the machine is indeed helping to make her work easier.
According to the principles of simple machines, the machine does not decrease the total work (the product of force and distance) but alters the way the force is applied.
In this case, the machine is potentially increasing the distance over which Mary applies the force so that the force required at any given moment is less, even though the total work done remains the same. This is known as the mechanical advantage provided by simple machines like levers, pulleys, and gears.
It's essential to remember that while simple machines allow us to apply less force, they require us to do so over a greater distance.
For example, a pulley system enables a person to lift a heavy object by pulling down on a rope over a longer distance than the object is lifted up, thus reducing the input force needed. The conservation of energy principle reinforces the idea that the total amount of work done remains constant. Consequently, simple machines help us perform the same work with an easier, reduced effort at the expense of increased distance.