What is Work? Work – The product of force and distance when a force moves an object a distance. In order for you to do work on an object, the object must move some distance as a result of your force. In order for you to do work on an object, the force you exert must be in the same direction as the object’s motion.

Calculating Work Work = Force x Distance W = F x D The amount of work done on an object can be determined by multiplying force times distance. Joule – a unit of work = to one newton-meter

Sample Problem To help rearrange the furniture in your classroom, you exert a force of 20 N to push a desk 10 m. How much work do you do? Analyze You know the force on the desk and the distance the desk moved. You want to find the amount of work done. Write the formula Work = Force x Distance Substitute and Solve Work = 20 N x 10 m Work = 200 Nm or 200 J Think about it The answer tells you that the work you do on the desk is 200 J.

Practice Problem #1 A hydraulic lift exerts a force of 12,000 N to lift a car 2 m. How much work is done on the car? Analyze You know the force on the car and the distance the car moved. You want to find the amount of work done. Write the formula Work = Force x Distance Substitute and Solve Work = 12,000 N x 2 m Work = 24,000 Nm or 24,000 J Think about it The answer tells you that the work you do on the car is 24,000 J.

Practice Problem #2 You exert a force of 0.2 N to lift a pencil off the floor. How much work do you do if you lift it 1.5 m? Analyze You know the force on the pencil and the distance the pencil moved. You want to find the amount of work done. Write the formula Work = Force x Distance Substitute and Solve Work = 0.2 N x 1.5 m Work = 0.3 Nm or 0.3 J Think about it The answer tells you that the work you do on the pencil is 0.3 J.