Teacher Edition

EXPLORE NGAGE EXPLORE EXPLAIN ELABORATE EVALUATE Teacher Toolbox Identifying Preconceptions Students may initially have trouble understanding the concept of inertia. Inertia is the tendency of a moving object to keep moving and an object at rest to stay at rest. A force is not needed to keep an object in motion. If you slide a book across a table, the book will come to a stop because frictional forces are present, not because a force is absent. Inertia in Collisions 30 min whole class VOCABULARY As students are reading, encourage them to use context clues to derive the meaning of the vocabulary words. Remind students that they can use the glossary to further develop their understanding. Before Reading Have students observe the photos of the car and the blocks. Ask students to describe the motion they experience in the back seat of a car when the car makes a sharp turn. Lesson Vocabulary collision Tell students that a collision is a physical interaction between at least two objects. As students learn the vocabulary for this lesson, have them create an organizer to show the words. Talk About It Have students discuss what they observed in the Inquiry Activity, Toy Car Crashes, and whether the car collision activity demonstrated a contact or noncontact force. Students should support their argument with evidence they collected from the activity. Lesson 3: Energy Transfer in Collisions Inertia in Collisions When you hear the word collision , you probably think about a car crash. A car crash is a collision, but in science, collision has a broader definition. A collision occurs when two or more objects hit each other with a force. A baseball bat hitting a baseball is a collision. Your fingers pushing the keys on a keyboard are also collisions. Talk About It Recall what you learned about contact and noncontact forces in Lesson 1. Are collisions a contant or noncontact force? Explain your answer to a partner, and support your argument with evidence. Recall that inertia is the tendency of an object in motion to stay in motion and an object at rest to stay at rest. A force needs to act on an object to change the object’s inertia. Look at the photos of the toy car and the red block below. The car and the red block are moving together at the same speed. When the car collides with the wood block, the car’s inertia is changed. The force the car applies to the block and the force the block applies to the car are equal. This causes the car’s motion to stop. Notice what happens to the red block upon impact. The block continues to move forward after the motion of the car stops due to the block’s inertia. VOCABULARY Look for these words as you read: collision conservation of energy energy transfer The inertia of the red block keeps it moving after the car stops. Copyright © McGraw-Hill Education Matt Meadows/McGraw-Hill Education 48 EXPLAIN Module: Energy and Motion 041_060_NA_SCI_SE_G4_MAL3U1_699632.indd 48 02/01/19 1:21 PM GO ONLINE INTERACTIVE PRESENTATION ADDITIONAL RESOURCES Read About: Inertia in Collisions Lesson Vocabulary: Energy Transfer in Collisions Matt Meadows/McGraw-Hill Education 48 Module: Energy and Motion