Final answer:
The velocity ratio is greater than mechanical advantage in a simple machine due to frictional losses, where input force is partially converted to heat energy, reducing the actual force output.
Step-by-step explanation:
The reason the velocity ratio is greater than the mechanical advantage in a simple machine is primarily due to frictional losses. A machine's mechanical advantage is the ratio of output force to input force, indicating how many times a machine can multiply the input force. However, due to friction within the machine, some of the input work is converted to heat energy, thus not all input force can be converted to useful work. As a result, while the setup of the machine (such as the lengths of the levers or the slope of an inclined plane) predicts a certain velocity ratio, the actual force output is less than ideal due to these losses, leading to a mechanical advantage that is lower than the velocity ratio.