Work

Work

• Two conditions must be met in order for work to be done.

- an object must move

- a force must be applied to the object in the direction that the object moves.

Measuring WorkIf force is applied to an object to make it move, that force can be measured in newtons (N). If the objectcovers distance then that can be also be measured in meters (m). Therefore, the units for work are called

newton-meters (N/m).

Work

Work and Power

Calculating Work

W = f x dHow much work is done if a force of 50 N is applied to awagon which is pulled a distance of 5.3 m?

W = f x dW = 50 N x 5.3 mW = 265 Nm

Practice

• How much work would you do if you used 1000 N of force to push a car a distance of 103 m?

Problems Solved

#1 w = f x d

w = 1000N x 103 m

w = 103,000 Nm

• 7250 Nm of work is done over a distance of 25 m. How much does the object moved weigh in newtons?

Problems Solved

#2 f =wd

f =7250 Nm 25 m

f = 290 N

• How far will you move an object if you do 300 Nm of work using 60 n of force?

Problems Solved

#3 d = w f

d =300 Nm 60 N

d = 5 m

Work Reviewed

We have learned that if force is measured in newtons (N)and if distance is measured in meters (m) then the units for work are called newton meters. (Nm)newton meters. (Nm) Another unit for work is called the joule (J). 1 J = 1 Nm1J of work is the amount of work used when a force of 1Nmoves a 1 kg mass a distance of 1m.

Review:

Two criteria for work: - an object must move - a force must be applied in the direction of movement.Formula: - Work = force x distance W = f x d

UnitsNm or J

The End !