Work and EnergyAccording to Holt physical science, work is the “transfer of energy to a body by the application of a force that causes the body to move in the direction of the force” ( Holt 378). Work equals force times distance, which means that in order for something to work, it has to move. Energy is “the ability to do work” (Holt 73). Energy is transferred or transformed every time work is done. The work requires an object to undergo a change in position or movement, but the energy can be present even when it seems like nothing is happening. Both work and energy are measured in Joules. Work In order for work to be done, the force must cause a change in the position or motion of the object in the direction from which the force comes. This means that the object to which the force is applied must move in order for it to be considered work. So if you try to push a wall and the distance the wall travels is zero, the work done on the wall is zero. However you are working on the muscles of your body. Your muscles contract over and over and with each contraction a small amount of work is done, but after a while this can add up to a lot of work. “The distance (or displacement) in work is the distance from the starting point to the final point” (ducklings). So, if you take a book and then put it back in the same place, the distance is zero. “In the simple definition we use distance rather than displacement because the acting force can follow a windy path” (WORK, ENERGY AND POWER). Work is often measured in joules: newtons per metres, or NX m. One joule equals 1 kg X 1 kg at 1 it does not multiply the force, but it increases the distance and the speed” (Holt 383). If something has an MA of exactly 1 it means that the machine has no mechanical advantage or disadvantage. There are two types of mechanical advantages: mechanical advantage ideal (IMA) and effective mechanical advantage (AMA). The ideal mechanical advantage is the MA of an ideal machine. This means that the machine is 100% efficient, so it does not suffer from the effects of friction. There are no ideal machines, so it is theoretical and is calculated using the principles of physics. The equation for IMA is: IMA= distance effort/resistance distance. The actual mechanical advantage is the MA of a real machine. It takes things like friction into consideration. The equation for AMA is: AMA=resistance force/effective effort force.