Review

from Let's Do Science 3 – Text Book B

Sound

Review 1. List the forces that cause a ball to slow down and stop when it is rolled along the ground. 2. Describe and provide an example of a contact force. 3. True or false. Friction is a non-contact force. 4. List three forces that can act at a distance. 5. Why does a rocket need a large force to lift it into space? 6. True or false. An object at rest with zero net force acting upon it will remain at rest. 7. Describe what happens to an object when the forces acting on the object do not sum to zero. 8. Predict and describe the motion of the children. What are the forces that cause the motion? 14. When the forces acting on an object are , there is no change in motion. 15. When the forces acting on an object are , there is a change in motion. Regal to be the mo motion? education iod stop when t forc ce nce. e force to lift i with zero n an objec is a change

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A Closer Look Magnetic Resonance Imaging (MRI)

Did you know that magnetic force can be used to create images of the inside of your body?

Some hospitals have large donutshaped devices called MRI machines. MRI stands for Magnetic Resonance Imaging. So how does an MRI machine use magnets to see inside your body?

Patients lie on a bed and move through the donut-shaped cylinder which contains very powerful magnets. The magnetic force is turned on and off very quickly. Different parts of your body respond to the magnetic force in different ways. A computer records these changes and creates an image of the patient’s bones, organs and tissues.

ugh . The The nd offff of your netic c forceorce uter records records an image n image o rgans tissue

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MRI is very helpful. It allows doctors to s to diagnose problems by studying the e images without the need for surgery or ery or causing any pain to patients.

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Go Online!

Watch an MRI in action on the NGScience website. QuickCode: E5G1

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12 Forms of Energy

In this chapter you will ... • list and describe different forms of energy. • explain how sound is made and how it travels. • describe ways in which sounds can be different. • list sources and uses of light. • describe how heat moves and how heat is used by people. What is energy? How do people use energy in their everyday lives?ducatio erent how heat is useed people ryday lives? n