How does the mechanical advantage of a wheel and axle change as the wheel increases?

The mechanical advantage of a wheel and axle system increases as the diameter of the wheel increases relative to the axle. This is because a larger wheel requires less force to turn compared to a smaller wheel, allowing for a greater load to be moved with the same effort. Essentially, the ratio of the wheel's radius to the axle's radius determines the mechanical advantage, so a larger wheel amplifies this effect, making it easier to lift or move heavier loads.