TAKS Objective 4 The student will demonstrate an understanding of motion, forces, and energy.

TEKS 7.6 A Science concepts Demonstrate how unbalanced forces cause changes in the speed or direction of an object's motion;

 For Teacher’s Eyes Only What is a force? A force is a push or a pull.

What are examples of forces? Magnetism Electric force Wind Any push or pull made by an object or matter

Cause objects to start moving Cause objects to stop moving Change the motion of objects Nothing at all Balanced forces do not cause a change in motion. They are equal in size and opposite in direction. Unbalanced forces cause something to either change speed or change direction. What do forces do?

Forces occur in pairs and can be either balanced or unbalanced. Forces and Motion

Balanced Forces When forces are equal in size but opposite in direction.

Balanced forces result in: A net force of “zero”. The two forces pushing against each other are equal and cancel each other out. No motion

Forces that are not equal in size. Unbalanced forces always cause a change in motion. Unbalanced Forces

Unbalanced forces can also be exerted in the same direction. The forces are added together in the same direction the force is being applied. Unbalanced Forces

Example Two people combine to push a car off the road.

Forces in the same direction always combine by addition Forces in opposite directions always combine by subtraction. Balanced forces are always in opposite directions. How Forces Combine

Unbalanced forces either make something move or change the speed and/or direction of something that is moving. Balanced forces produce no motion (net force “zero”). How Forces Combine

Motion and machines Forces are used in machines to produce motion and make work easier.

Simple machines are devices that use only one type of motion to make work easier. They are used to change the size or direction of a force. What are simple machines?

What are the six simple machines? The six simple machines are: Lever, pulley, wheel and axle, inclined plane, wedge, and screw

Remembering the six simple machines? Little Wheeler Is Sick With Pinkeye Lever, Wheel and Axle, Inclined Plane, Screw, Wedge, Pulley

Lever A simple machine consisting of a bar that pivots around a fixed point, called a fulcrum

Three Types of Levers First Class Second Class Third Class

Inclined plane-a simple machine that is a straight slanted surface; a ramp Inclined Plane

Wedge A simple machine that is a double inclined plane; a wedge is often used for cutting.

Screw A simple machine that is an inclined plane wrapped around in a spiral around a central core.

Wheel and Axle A simple machine consisting of two circular objects of different sizes; the wheel is the larger of the two circular objects.

Pulley A simple machine that consists of a grooved wheel that holds a rope or cable.

 Engage 1.The teacher will walk around the room demonstrating balanced and unbalanced forces. Students will then discuss which forces produced motion and why. 2.Blow on a pinwheel Use magnet to move metal object Arm wrestle

 Explore Activity: Try and Force Me (Blackline Master) Objective 1: The learner will identify forces that produce motion. Objective 2: The learner will distinguish between balanced and unbalanced forces. Activity Overview: Students will observe different kinds of forces. They will determine what the agent, receiver, and affect of each force is.

Explain There are many types of forces: mechanical, electrical, magnetic, gravitational, friction, buoyancy, ect. A force is simply anything that produces a push or a pull.

Elaborate Activity: Finding Your Balance (BLACKLINE MASTER: Data Table – Finding Your Balance) Objective: The students will attempt to identify balanced and unbalanced forces from the Explore: Try and Force Me.

 Evaluate Visual Assessment: The teacher will rub a balloon with wool for 30 seconds. Then the balloon will be placed near tiny pieces of paper (.5 cm pieces of tissue work well) laying on a table.

 Evaluate Instruct the students to: Make observations. Explain what happened in terms of forces.

Engage The teacher will read this entertaining story of a real accident report to introduce forces in simple machines. It was published by Charles Allbright of the Arkansas Traveler.

 Explore Activity: Keep it Simple! (Blackline Master) Objective: The learner will identify the six types of simple machines from pictures of everyday tools. Activity Overview: Students will read the descriptions of the six simple machines and place pictures of simple machines into categories.

Exploration 2 Activity: Name That Force! (Blackline Master) Objective: The learner will identify where forces are located in using simple machines, and where the critical force occurred to produce motion. Activity Overview: Students will assemble in groups of three or four and answer the following questions: In each of the pictures, tell what forces are involved to produce motion. Explain where the force in each picture is applied to produce motion. Explain where the critical motion takes place in each picture.

Explain Pulleys are used to make work easier. By either changing the size or the direction of the force. In this activity, only the direction of the force was changed. At any point you could suspend the mass in the air and stop pulling down on the rope. Then the forces would be balanced.

Elaborate Activity: Just Hangin’ Around (Blackline Master) Objective: The learner will build a mobile made out of balanced levers. The students will make a mobile out of balanced levers.

Elaboration 2 Activity: Pull Me Up! (Blackline Master) Objective: The learner will use a pulley to demonstrate how simple machines multiply force. Activity Overview: Students will use a simple fixed pulley, and a block and tackle to compare how pulleys multiply force.

Elaboration 3 Construct Rube Goldberg Machine It must include an example of all six simple machines and must accomplish a simple task of the students’ choice.

 Evaluation Using the Rube Goldberg machine, students will identify the 6 simple machines and explain how they work to produce force and motion.