How do machines use energy and momentum

It is easier for humans to carry 10 pounds up steps than to carry pounds up 10 steps, even though the total mechanical energy required for both jobs is exactly the same. Even though the total mechanical energy required is the same, one job is easier because human muscles operate more efficiently at low intensities for a long time. If a person tries to carry pounds up 10 steps, he would waste a lot of energy that would end up as heat because of the inefficiency of human muscle for such a task.

All simple machines — levers, pulleys, ramps, screws, gears, etc — operate on this same principle. But the total work and total energy expended for a given job is always they same, no matter what machine you use. Topics: conservation of energy , distance , energy , force , free energy , lever , overunity , simple machines , work.

Levers maximize force by minimizing distance, but the energy inputted is the same. In this image, the length of the arrow represents the distance over which the force is applied and the width of the arrow represents the magnitude of the force. Plan your visit. A diver or gymnast may also suddenly flip or twist much faster.

This speeded-up rotation results from a sudden redistribution of mass. You can make yourself suddenly spin faster while sitting in a rotating chair. Have your partner start rotating you slowly, then have that person let go and move away as the chair continues to turn. Newton found that an object in motion tends to remain in motion, in a straight line and at a constant speed, unless it is acted upon by a net force.

Today, we call this observation the law of conservation of momentum. The momentum of an object is the product of its mass and its velocity.

There is an equivalent law for rotating objects. A rotating object tends to remain rotating with a constant angular momentum unless it is acted upon by an outside twisting force. The definition of angular momentum is more complex than that of linear momentum. Angular momentum is the product of two quantities known as angular velocity and moment of inertia. Angular velocity is merely velocity measured in degrees, or radians-per-second, rather than meters-per-second.

Mechanical energy can be either kinetic energy energy of motion or potential energy stored energy of position. A moving car possesses mechanical energy due to its motion kinetic energy. A moving baseball possesses mechanical energy due to both its high speed kinetic energy and its vertical position above the ground gravitational potential energy.

A World Civilization book at rest on the top shelf of a locker possesses mechanical energy due to its vertical position above the ground gravitational potential energy. A barbell lifted high above a weightlifter's head possesses mechanical energy due to its vertical position above the ground gravitational potential energy.

A drawn bow possesses mechanical energy due to its stretched position elastic potential energy. An object that possesses mechanical energy is able to do work.

In fact, mechanical energy is often defined as the ability to do work. Any object that possesses mechanical energy - whether it is in the form of potential energy or kinetic energy - is able to do work.

That is, its mechanical energy enables that object to apply a force to another object in order to cause it to be displaced. Numerous examples can be given of how an object with mechanical energy can harness that energy in order to apply a force to cause another object to be displaced. A classic example involves the massive wrecking ball of a demolition machine. The wrecking ball is a massive object that is swung backwards to a high position and allowed to swing forward into building structure or other object in order to demolish it.

Upon hitting the structure, the wrecking ball applies a force to it in order to cause the wall of the structure to be displaced. The diagram below depicts the process by which the mechanical energy of a wrecking ball can be used to do work. A hammer is a tool that utilizes mechanical energy to do work. The mechanical energy of a hammer gives the hammer its ability to apply a force to a nail in order to cause it to be displaced.