They improve efficiency by allowing persons who work best in a low-force, long-distance mode to complete a high-force, short-distance assignment. However, regardless of the equipment used, the total effort and total energy used for a specific job are always the same. That is, if 10 people each use a hand-powered shovel to dig one hole, then all together they will have dug 11 holes. In other words, a machine or tool can only replace human labor; it cannot do things that humans do better than machines. Humans still go to work every day using tools like levers and motors because situations arise that only these mechanical devices can fill. As an example, suppose that two people are needed to open each bottle of soda but that one person can open 100 bottles per hour and the other person can open only 20 bottles per hour. If they were to work together, they would need a machine to help them out. Machines can be used as levers to increase efficiency because they allow one person to do the work of two or more people. In this case, the machine acts as a lever since it increases the force applied to the bottle cap. Another example involves the use of motors instead of human power to drive machinery. Human power is not enough torque (rotation) to drive most machines so they must be powered by motors.