Which expression represents work?

Which expression represents work?

• A. Force × distance
• B. W = F × d
• C. W = mgh
• D. Energy equals work

Answer: (B)

Work is the transfer of energy that occurs when a force moves an object a certain distance in the direction of the force. For a constant force acting along the path, the amount of work is the product of the force and the distance moved: W = F × d. This shows how energy is transferred more when the force is larger or the object moves farther in the direction of that force. If the force isn’t exactly in line with the motion, only the component of the force in the direction of the movement contributes, so W = F d cos theta. The unit is the joule, which is a newton-meter. The expression W = m g h refers to changes in gravitational potential energy, not the general work done by any force. And saying energy equals work isn’t quite right, since work is the process of transferring energy, not the energy value itself. For example, pushing with 5 N for 3 m along the direction of motion results in 15 J of work.

Work is the transfer of energy that occurs when a force moves an object a certain distance in the direction of the force. For a constant force acting along the path, the amount of work is the product of the force and the distance moved: W = F × d. This shows how energy is transferred more when the force is larger or the object moves farther in the direction of that force. If the force isn’t exactly in line with the motion, only the component of the force in the direction of the movement contributes, so W = F d cos theta. The unit is the joule, which is a newton-meter.

The expression W = m g h refers to changes in gravitational potential energy, not the general work done by any force. And saying energy equals work isn’t quite right, since work is the process of transferring energy, not the energy value itself. For example, pushing with 5 N for 3 m along the direction of motion results in 15 J of work.