Work

What is work? In science, the word work has a different meaning than you may be familiar with. The scientific definition of work is: using a force to move an object a distance (when both the force and the motion of the object are in the same direction.) Draw a diagram showing work.

Work or no work? Work; the force and the movement of the object are in the same direction.

Work or No work? No work the force and the direction the object are moving are in different directions. No work the wall is not moving.

No there is no movement.

Work is the transfer of energy through motion. Determine if the following statements show work or no work being done and why.

A scientist delivers a speech to an audience of his peers. No, nothing has been moved. A body builder lifts 350 pounds above his head. Yes, the weight has been moved A mother carries her baby from room to room, the force is the mom’s arm holding the baby. No, the baby has not been moved away from the mother, A father pushes a baby in a carriage. Yes, the carriage has been moved.

A woman carries a 20 kg grocery bag to her car the force is the woman’s arm holding the grocery bag. No, the grocery bag has not been moved in the direction of the force.

Work = Force x distance The unit of force is newtons (N) The unit of distance is meters (m) The unit of work is newton-meters (Nm) One newton-meter is equal to one Joule (J) So the unit of work is a joule (J)

Formula for Work W = Fd Work = Force x Distance W --------- F * d

W = F d Work = Force x Distance Calculate: If a man pushes a concrete block 10 meters with a force of 20 N, how much work has he done? W = Fd W = 20N x 10m 200 Nm = 200 J

Check for Understanding A weight lifter lifts a 500-N weight a distance of 2 m from the floor to a position over his head. How much work does he do? Explain your answers.

F = 500 N Distance = 2m Work = Force x Distance W = F x d W = 500 N x 2 m = 1,000 Nm = 1,000 Joules The work that the weight lifter does is 1,000 Joules.