# Simple Machines and MA Day 31.

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Simple Machines and MA Day 31

Essential Question Why use simple machines?

Learning Targets I can explain mechanical advantage using pulley systems.

Explore: Main Idea Directions: As a group on one clean sheet of paper, in coloring pencil write the following table. As a group discuss what the main idea is for each set of terms/statements and write it at the top of the column. Action-Reaction Lifting a Box 2m A horse pulling a crate in 10 mins Screw F=m(a) Pushing A Rock 2m Pushing A Rock in 2 mins Wedge Weight Pulling a Crate 10m Pulling a crate 2 mins Pulley Gravity Carrying A Book Lifting a box 1 mins Lever Inertia Wheel and Axe Inclined Plane

Teacher Demonstration: Pulleys and mechanical advantage
Materials: Yarn Rollers Stand w/clap ring Different Masses Procedure 1.) Construct a one roller pulley with different masses. 2.) Explain the pulley as you show the students how to works. Make sure to use force, distance, mechanical advantage (less effort), input force, output force. 3.) Do with 2 rollers, 3 rollers. 4.) Show Mechanical advantage by counting the number of ropes.

Directions: On the right-side, Complete the two steps. 1. Write the definition for Mechanical Advantage 2. Create a T-chart for Mechanical Advantage for Force and Mechanical Advantage for Distance using the notes provided on simple machines and mechanical advantage. T-chart should include: Formula for MA=Force and MA=Distance Definitions for output force, input force, distance effort, and distance resistance. Give one example of MA=force and MA=distance

Teacher Explain Input/Output Force

Explain: MA of Force Directions: Where is the input force and output force located? B. A.

Direction: Label as Input force or Output Force. You lift a 200N object. A wedge applies 400N of force to a piece of wood. You push 240N on a lever. You turn a screw with 30N of force. A pulley applies 48N of force up.

Explain: MA of Distance
Directions: Where is the distance effort and distance resistance?

Direction: Label as distance effort or distance resistance. You use an incline plane to lift a car up 4 meters. You use a 10 meter ramp to raise up a car. You lift a 200kg object up 2meters. The distance you push down on a lever. The distance the object moves with a lever.

Mechanical Advantage can also be calculated by counting the number of ropes in a pulley. Directions: What is the MA in each pulley?

Explain: MA Direction: What is the distance mechanical advantage of the following diagram? Make sure to show the formula and show how you got the answer.

Direction: What is the force mechanical advantage of the following diagram? Make sure to show the formula and show how you got the answer.

Explain: Efficiency Efficiency in science means…
a.) Formula is output work/input work x 100% Wo x 100% Wi b.) amount of energy lost in a system Efficiency wants to be at 100% but NO machine has 100% efficiency you loose it to heat, friction, sound, etc.

Exit Slip: MA Write the formulas for Mechanical Advantage

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