Forces and Motion

1. Forces and Motion

2. How Can You Describe Motion? • Directed Inquiry • Objective • You will describe the motion of various objects (for example, forward, circular, wave). • Complete Directed Inquiry Activity

3. How Can You Describe Motion? • How To Read Science • Objective • You will use a variety of strategies to monitor reading in (for example, rereading, self-correcting, summarizing, checking other sources, class and group discussions, reading on, trying alternative pronunciations, asking questions). • Summarizing • Suppose you just saw a movie your friend did not see. How would you tell your friend what the movie is about? • Read, “How to Read Science”

4. How Can You Describe Motion? How to Read Science

5. Section 1: What Happens When Things Change Position? • Objective • You will describe the motion of various objects (for example, forward, circular, wave). • Quick Activity Game • Purpose • You are going to read to understand speed and direction of an object's motion. • Summary • An object is in motion when it changes position.

6. Section 1: What Happens When Things Change Position? • Questions • How can you describe circular motion? • Can you think of something that moves in a circular motion? • How might you make an object move up as well as forward? • http://www.youtube.com/watch?v=odGx5JajnHU

7. Section 1: What Happens When Things Change Position? • Objectives • You will be able to list ways to view objects in relation to other objects. • You will describe ways to view the motion of objects in relation to each other and the background. • Summary • An object's position depends on, or is relative to, the position of other objects around it. • Maps model the position of places or objects relative to each other. • Change in the direction of motion of one object changes the relative position of other objects.

8. Section 1: What Happens When Things Change Position? • Activity • Draw a map of the classroom • Put yourself on the map and draw the classroom around you • If an object is in front of you, what are two ways you could change your position to put the object behind you?

9. Section 1: What Happens When Things Change Position? • Questions • After you pass by an object, what is its position relative to you? • What do the position, direction, and movement of an object depend on? • After you get to the lunch room, how could you describe a journey from the lunch room back to your starting position?

10. Section 1: What Happens When Things Change Position? • Objective • You will know that an object may move in a straight line at a constant speed, speed up, slow down, or change direction dependent on net force acting on the object • Summary • Speed is the rate at which an object moves, or changes position. • Speed can be fast or slow, constant or variable. • Objects that continue to move at the same rate are at constant speed; those whose rate changes as they move are at variable speed. • http://www.youtube.com/watch?v=y2Gb4NIv0Xg • Activity • As we read you are going to write a summary of each section

11. Section 1: What Happens When Things Change Position? • Questions • What do we call the rate at which an object changes its position? • What does it mean when you say that an object moves at a constant speed? • How does the motion of two bumper cars change when they bump into each other?

12. Section 2: How Does Force Affect Motion • Objective • You will know that the more massive an object is, the less effect a given force has. • Quick Activity • Why do you think one ball traveled farther than the other? What would you have to do to get the other ball to move as far? • Purpose • The purpose for reading is to understand what causes objects to change position and speed.

13. Section 2: How Does Force Affect Motion • Summary • A force is a push or pull. It changes the position, direction of motion, or speed of an object. • Change in position and speed depends on the amount of force and the mass of the object. • Friction opposes the motion of an object. • http://www.youtube.com/watch?v=qUIB1ugvDwE • http://www.youtube.com/watch?v=a5SOCxYft20 • http://www.youtube.com/watch?v=faUhTOm9xWU • http://www.youtube.com/watch?v=R7JMBqgl0Hc

14. Section 2: How Does Force Affect Motion • Questions • What two factors affect how much an object moves? • Why does it take more force to push a full shopping cart than it does an empty cart? • If you roll a ball, would it move farther before stopping on a tile floor or a parking lot? Why?

15. Section 2: How Does Force Affect Motion • Objectives • You will know that the motion of an object is determined by the overall effect of all the forces acting on the object. • Summary • Forces in the same direction can combine to have a greater effect on an object. • Opposing forces can combine to affect the motion of an object.

16. Section 2: How Does Force Affect Motion • Questions • During a tug-of-war, when will the rope not move? • What would happen in a tug-of-war if someone on one side let go of the rope? • How does the force of friction change if the ground under both tug-of-war teams becomes wet and slippery?

17. Section 2: How Does Force Affect Motion • Objective • You will describe kinds of forces that can cause motion. • http://www.youtube.com/watch?v=hZi8TXtRRYg&feature=related • Summary • Gravity is a non-contact force that pulls all objects toward each other. • Mass and distance affect the amount of attraction, or pull, of gravity. • Weight is the amount that gravity pulls on the mass of an object. • Magnetism is a non-contact force. A magnet attracts objects that contain iron.

18. Section 2: How Does Force Affect Motion • Questions • What is weight? • The Moon has less mass than the Earth. How would your weight be affected if you were on the Moon? • Why are gravity and magnetism considered non-contact forces?

19. Section 3: How Do Simple Machines Work? • Objectives • You will explain how forces can be harnessed to perform work. • http://www.youtube.com/watch?v=grWIC9VsFY4 • Purpose • You will read to understand what work is and how it can be made easier. • Summary • Work is applying a force to move an object over a distance. • http://www.youtube.com/watch?v=K3S6WKJIohw • Work is done when an object's position changes; if an object does not move, no work is done.

20. Section 3: How Do Simple Machines Work? • Questions • What two things do you need to know in order to determine the amount of work you do? • When does a magnet do work? • What could the children pictured in the snow on page 338 do to move the large snowball?

21. Section 3: How Do Simple Machines Work? • Objective • You will know the six types of simple machines (screw, inclined plane, wedge, pulley, lever, and wheel and axle). • Summary • Simple machines help make work easier. • Four kinds of simple machines are the inclined plane, the wedge, the screw, and the lever. • http://www.youtube.com/watch?v=wWPiY6Of6-U • http://www.youtube.com/watch?v=eOzNVBX-SX0

22. Section 3: How Do Simple Machines Work? • Questions • What simple machine is an inclined plane wrapped around a center post? • How does an inclined plane help you do work? • How are a wedge and a screw related to an inclined plane?

23. Section 3: How Do Simple Machines Work? • Summary • A wheel and axle makes work easier when the wheel is turned. • A wheel and axle makes objects on the wheel move great distances with short turns of the axle. Much force must be supplied to turn the axle. • A pulley is a wheel with a rope passed over it. It changes the direction of motion when a force is applied.

24. Section 3: How Do Simple Machines Work? • Questions • Where is the axle attached to a wheel? • Why is the distance around a wheel greater than the distance around its axle? • How does a pulley work to pull an object up when you are pulling down?