Login to Nearpod and answer the warm-up questions… Nearpod code is on the right of the EQ.

EQ: What is mechanical efficiency? Listen to me read the EQ. Ladies, read the EQ backwards. Gentlemen, stand up and read the EQ backwards. Type the EQ on your iPad. Select the two most important words. What will you know at the end of class?

Lesson Importance: WHY? Why do you need to know what mechanical efficiency is? Think… What does the word efficiency mean? Think a little longer… Share with your group. Type your answer.

Guided Practice: Machine Efficiency Mechanical/machine efficiency measures how well a machine converts input energy, work , and power into OUTPUT energy, work , and power.

TAPPLE What does machine/mechanical efficiency measure?

The efficiency of an ideal machine is 100% b/c the input work = output work. However, real machines do not achieve an efficiency of 100% b/c heat may be lost from the system due to friction between moving parts.

What is the ideal efficiency of a machine? 50% 75% As close to 100% as you can get 100%

An important way to improve the efficiency of a machine is to reduce friction. For ex: a pulley w/ a rope running a wheel is more efficient than a pulley where the rope only runs over a bar. The spinning wheel is the 1st example reduces friction and makes the machine more efficient.

CLOSE: answer on iPad What do you need to reduce to improve efficiency?

Review before we work on paper plate project… What is the definition of WORK?

WORK To apply a force to an object & the object moves a distance. Are these examples demonstrating work?

Is this example demonstrating work? Steve holding a door open. Bilawal picking up his science notebook. Anna pushing her chair in under her desk. Daniel who tried to push his bicycle out of the mud.

Spring Scales They measure two things… Newtons (force) and Weight (pounds or grams) HOWEVER, the main purpose is to measure NEWTONS. Newtons tell us how much force is required to move an object up an inclined plane.

Spring Scale

Don’t get confused… DOES A SIMPLE MACHINE REDUCE YOUR AMOUNT OF WORK? OR AMOUNT OF FORCE REQUIRED TO DO WORK?

Lever Review… If you wanted to move or lift a heavy object using a lever where would you move the fulcrum? You would want to move the fulcrum to the object that is HEAVIEST. The farther you are away the easier it will be to lift.

PAPER PLATE PROJECT Each definition…10 points Each example…3 points Each picture…3 points Color… 4 points **DUE ON TUESDAY, OCT. 11th