Final answer:
A lever is a rigid object that pivots around a fixed point called a fulcrum, functioning by principles of torque and leverage. The distance from the fulcrum, or lever arm, is crucial in determining the lever's mechanical advantage, which affects the force applied and exerted at the ends of the lever.
Step-by-step explanation:
A lever is a rigid object that rotates around a point called a fulcrum. In the study of physics, levers are one of the simplest machines and involve the principle of torques, as there is rotation about a pivot point. The distances from the pivot, or the lever arm, are significant factors in determining the lever's mechanical advantage (MA), which is an expression for the efficiency with which a lever can multiply force. A force applied to one end of the lever arm causes a force to be exerted on the other end, which could be either larger or smaller depending on where the fulcrum is located relative to the input and output forces.
A wheel and axle is a type of lever where the effort arm can rotate fully around the fulcrum. In the context of levers, force applied closer to the fulcrum over a shorter distance can cause the opposite end to move a greater distance, which is a principle seen in tools like baseball bats, hammers, and golf clubs. Similarly, the crank is a type of lever which is usually designed to have a large MA.