By definition, work is the transfer of energy as a result of applying a force over a distance. In physics, work has a very specific meaning. Work is the transfer of energy as a result of applying a force over a distance.
Therefore to calculate work, you multiply the force by the distance the object moves in the direction of the force. If you lift a block with a weight of one newton for a distance of one meter, you do one joule of work. Work is done on objects. If you lift a block one meter with a force of one newton, then you have done one joule of work on the block. It is important to remember in the calculation of work that the force and distance are in the same direction. Not all force does work. If you push down a book on the table, you have done zero work because despite the force you applied, the distance is zero as the book didn't move downward through the table.
Work & EnergyEdit
Without energy, it is impossible to do work. One way to think about energy is as stored work. Therefore, both work and energy are measured in the same units because work is a form of energy. But having energy doesn't always mean you can do work. The energy may be transferred to the object you apply the force to, or it may go somewhere else. For example, when you did work by sliding a book across the table, but the book wouldn't slide back all by itself. In other words, your work didn't give the book energy, or ability to do work. Instead, your work was done to overcome friction. The block did gain a tiny bit of energy because its temperature did increase slightly due to friction. However, that slight increase in energy was from the force of friciton, not your applied force.