1 Work Mrs. Anna Ward Ridge Road MS

Do Now!!! Page 39  What does Newton’s First law state?  Caia and Alexandria are pushing Mrs. Ward on a rolling chair down the hallway. They travel 27 meters in 9 second. What is Mrs. Ward’s speed?  What law deals with Action-Reaction pairs? 2

Announcements  Picture Day  Tests from Yesterday  Class Dojo updates 3

Brain Pop!!!!  orcesandtime/work/preview.weml orcesandtime/work/preview.weml orcesandtime/work/preview.weml 4

5 What is work?  In science, the word work has a different meaning than you may be familiar with.

WORK  Work is the using a force to move an object a distance (when both the force and the motion of the object are in the same direction.) 6

7 Work or Not?  According to the scientific definition, what is work and what is not? a teacher lecturing to her class a teacher lecturing to her classOR a mouse pushing a piece of cheese with its nose across the floor a mouse pushing a piece of cheese with its nose across the floor

8 Work or Not?  According to the scientific definition, what is work and what is not? a teacher lecturing to her class a teacher lecturing to her class a mouse pushing a piece of cheese with its nose across the floor a mouse pushing a piece of cheese with its nose across the floor

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10 What’s work?  A scientist delivers a speech to an audience of his peers.  A body builder lifts 350 pounds above his head.  A mother carries her baby.  A father pushes a baby in a carriage.  A woman carries a 20 kg grocery bag.

11 Formula for work Work = Force x Distance  The unit of force is Newtons  The unit of distance is meters  The unit of work is newton-meters  One newton-meter is equal to one joule  So, the unit of work is a Joule

12 CFU: W=FD Work = Force x Distance Calculate: If a Kevin pushes a concrete block 10 meters with a force of 20 N, how much work has he done?

CFU: #2  If Mr. Beavers pushes a technology cart to the media center 20 meters away with a force of 50 N, how much work has he done? 13

CFU #3  If a train pulls a cargo with a force of 20,000 N for 1000 m, what work was done? 14

15 Power   Power is the rate at which work is done.   Power = Work * /Time * (force x distance)   The unit of power is the watt.

Finally, Mechanical Advantage…  In work, you often use machines to make the work easier.  Machine have: input force (the force you apply) input force (the force you apply) output force (force which is applied to the task) output force (force which is applied to the task)  A Mechanical Advantage occurs when in the Input Force is less than the output force. 16

Mechanical Advantage  The greater the mechanical advantage, the more effective the machine is because YOU are not having to work as hard. 17

EXIT TICKET How much work would it take to push a box with a force of 60N for 100 meters? 18