Unit F Chapter 2

Ch 2 Lesson 1 Investigation Have you ever been on a moving bus, car or train? What happens if you your standing and the vehicle starts, stops, speeds ups, slows down or turns? This investigation will help you observe changes in motion.

Directions 1. Predict what will happen to the air bubble if you turn the bottle to the left or right. Turn the bottle and observe what happens. Record your observations. 2. Predict what will happen if to the air bubble if you move the bottle ahead at a study speed. 3. Predict what will happen if you increase the bottle’s speed. Record your observations

Ch 2 Lesson 1 Motion & Speed Position is an object’s place or location. If an object’s position changes the object’s in motion. Frame of reference To determine if an object’s in motion depend on your frame of reference. For example: A girl is riding her bike. In the basket of her bike is a book. To the girl the book isn’t moving. To someone watching the girl, the book would appear in motion.

Speed & Velocity Speed is a measure of the distance an object moves in a given amount of time. Average speed is calculated: Total distance ÷ amount of time If you travel 10miles in 5 minutes your average speed would be 2miles per hour Velocity is an object’s speed in a specific direction. If two objects are traveling at the same speed but one is moving North and the other South, their velocity would be different.

Acceleration & Momentum When an object starts, stops, speeds up, slows down, or turns left or right, it changes velocity. Acceleration – is any change of velocity. Slowing down is called deceleration. The ONLY time you don’t accelerate is when you are moving in straight line at a constant speed.

Have you ever ridden in a car and the driver suddenly slams on the brakes? What happens?

Momentum Momentum is the measure of how hard it is to slow down or stop an object. If two objects have the same velocity, the one with the greater mass has more momentum. If two objects have the same mass, the one with the greater velocity has more momentum. WEAR YOUR SEAT BELT!!!!!

Review Questions 1. Two objects move for the same amount of time. Object A moves farther than Object B. Which object moved at a greater average speed. 2. Explain how velocity differs from speed. 3. An object speeds up. Then it slows down. Then it changes direction. Which of these are examples of acceleration? 4. Use the idea of momentum to explain why a football coach might choose a large, faster runner to carry the ball. 5. If you observe a change in an object’s speed or direction, you are observing a change in its? a) Frame of reference b) Velocity c) Position d) Momentum

Answers 1. Object B 2. Velocity is speed in a specific direction. 3. All of them are examples of acceleration. 4. The faster the velocity and the more mass an object has the more momentum it has. The more momentum an object has the harder it is to stop. 5. C. position

Ch 2 Lesson 2 Investigation Watch as the car goes down the ramp. Observe what happens to the dime. Measure and record the distance. Now observe as we replace the dime with a quarter and observe what happens. Measure and record the distance. Predict what will happen if we raise the ramp. Measure and record the distances.

Ch 2 Lesson 2 Newton – changed the way scientist observe the natural work. Before him, scientist believed elements moved toward each other. Newton developed 3 laws of motion to explain how objects on Earth move.

Newton’s First Law An object at rest will remain at rest, and an object in motion will continue moving in a straight line at a constant speed until an outside force acts on it. The property of matter that keeps it moving in a straight line or keeps it at rest is called inertia. First Law

Newton’s Second Law An object’s acceleration depends on the size and direction of the force acting on it and on the mass of the object. Second Law

Newton’s Third Law For every action, there is an equal and opposite reaction. Action force- the first force. Reaction force – the force that pushes or pulls back. Third Law

Review Questions 1. If an astronaut throws an object into space, what happens? 2. A truck and a falling leaf collide. The leaf accelerated rapidly. What doesn’t the truck? 3. Explain what happens when a person pushes on a stuck door. 4. Suppose a golf ball and a bowling ball are rolled toward each other. When they collide, the bowling ball stops. How does the golf ball’s speed compare to with the bowling ball’s speed? 5. What is the property of matter that keeps it moving in a straight line in a same speed. a. inertia b. mass c. momentum d. velocity.

Video Quiz Online Video Quiz In pairs, watch the online video than complete the quiz at the end. Worksheets are provided to record your answers.

Ch 2 Lesson 3 Orbits Is the path one body in space takes as it revolves around another body An example of the first law of motion, an object in motion will continue in a straight line until another object acts on it. Remember this is called inertia. So what causes it to orbit? Universal Law of Gravitation – is all objects in the universe are attracted to all other objects. Combined with inertia this explains why planets orbit. Inertia keeps them moving in a straight line, gravity pulls it toward Earth.

Continued.. So the moon orbits the Earth, and the Earth orbits the sun. Earth’s orbit around the sun is elliptical.

Review Questions 1. What is an orbit 2. What keeps Earth in orbit around the sun? 3. What is the law of universal gravitation? 4. Suppose the gravitation between Earth and the sun suddenly stopped. What path would Earth follow? 5. Gravitation between Earth and the moon pulls on the moon as the moon orbits. What property of the moon keeps it from crashing into Earth? a. gravitation b. inertia c. mass d. momentum