Work  When a force causes an object to MOVE in the DIRECTION of the force.  Calculated using the equation:  Force x Distance  F x d  Units  Newton x meter  Nm  Joules (J)  Units  Newton x meter  N·m  Joules (J) ForceMotion

 Marla pushes a box across the hall. –Was a force applied? –Did the object move as a result of that force? –Did the movement go in the direction of the force? –Yes to all Work Was Done  Marla carries a box across the hall. –Was a force applied? –Did the object move as a result of that force? –Did the movement go in the direction of the force? –Yes, No, No Work was not done Was work done?

HOW MUCH WORK?  A man applies a force of 500 N to push a truck through a distance of 100m. How much work does he do? 500 x 100 : 50,000 Joules

Now how much?  Suppose you lift a 75 N bowling ball 2 m off the floor. How much work do you do? 75 x 2 = 150 Joules

One more time  How much work is required to lift two 50 N bowling balls 1 m off the floor? ( ) x 1 = 100 Joules

Now your turn to practice  Please place some yarn around your book. Make sure it is tied.  Place the yarn on the spring scale hook.  Pull the book slowly across the table using the spring scale. (This measures force)  Measure the time it took you to pull the book and measure the distance the book traveled.  You can now calculate work and power. Write all data in your journals.

Thank you Thank you  Your work is done here today.  You will complete a worksheet on the meaning of work in class tomorrow.