Physics Grade 9 - Motion Revision PDF

PHYSICS GRADE 9 LESSON 6- Motion – revision Motion Motion occurs when an object changes its position relative to a reference point over time. Distance: Definition: The total length of the path traveled by an object, regardless of direction. Unit: Meters (m) scalar quantity...

PHYSICS GRADE 9 LESSON 6- Motion – revision Motion Motion occurs when an object changes its position relative to a reference point over time. Distance: Definition: The total length of the path traveled by an object, regardless of direction. Unit: Meters (m) scalar quantity Represented as x, d or s To know the total distance just sum all the distance available Displacement: Definition: The shortest straight-line distance from the initial position to the final position, considering direction. Displacement is also a vector quantity. Measured in meter (m) Represented as x, d or s What is the difference between distance and displacement? What is the similar thing between distance and displacement? SPEED Definition: The rate at which an object covers distance. It does not take direction into account (a scalar quantity) VELOCITY Definition: The rate at which an object changes its displacement (a vector quantity, meaning it includes both magnitude and direction). What is the difference and similarity between velocity and speed.? Uniform motion The object covers equal distances in equal time intervals. Non uniform motion The object covers unequal distances in equal time intervals. PHYSICS GRADE 9 LESSON 4,5- Motion -Non uniform motion and Displacement using velocity time graph RECAP!!!!!! WHAT IS MOTION? Motion occurs when an object changes its position relative to a reference point over time. Uniform motion? The object covers equal distances in equal time intervals. Instantaneous speed: The speed of an object at a specific moment. Average speed: Total distance divided by total time. Non uniform motion Non-uniform motion happens when the speed of an object changes as it moves. The object covers unequal distances in equal time intervals. Non uniform motion In non uniform motion we have: An increase in speed (positive acceleration). A decrease in speed (negative acceleration or deceleration). Acceleration measures how quickly an object’s velocity changes over time. It can be positive (speeding up) or negative (slowing down, also called deceleration). Speeding up If an object covers more distance than before in each second this motion is called speeding up. Uniform vs non Uniform Slowing down If an object travels less distance than before in each second, this motion is called slowing down. Displacement using the velocity-time graph Displacement is the shortest distance between an object’s starting point and its final position, along a straight line. It includes direction, so it's a vector quantity. Velocity is on the y-axis (vertical axis). Time is on the x-axis (horizontal axis). The area under the velocity-time graph gives us the displacement of the moving object. Types of graphs Distance time graph - distance on the vertical and time on horizontal. The line describing the motion is the speed. Velocity time graph - velocity on the vertical and time on horizontal. The line describing the motion is acceleration. The area of the graph is displacement. Exercices recap LESSON 3,4- Motion- Instantaneous speed, Uniform motion, Graphing motion Instantaneous speed Instantaneous speed is the speed of an object at a specific point in time. Example : The speedometers of cars, motorcycles. when you read the speed on any speedometer, it is the instantaneous speed of the vehicle. Instantaneous speed is different from average speed, which is calculated over a longer time interval. Instead, instantaneous speed is what a speedometer in a car shows at any particular instant. where X is the position of the object and T is the time. Vinst – Instantaneous Speed Exercise 1: Walking in the Park Ana walks in a straight line in the park. Between 10 seconds and 12 seconds, she walks 6 meters. Question: What is Ana’s instantaneous speed at the 11-second mark? Exercise: Swimming Competition Maria swims 10 meters between the 6-second and 7-second marks in a swimming competition. Question: What is Maria’s instantaneous speed at the 6.5-second mark? Uniform Motion Uniform motion occurs when an object (a car) travels equal distances in equal intervals of time, A car moving at a constant speed. The car shown in the figure travels equal distances in the same time intervals, so it performs uniform motion. A car moving at a constant speed of 5 m/s along a straight road is in uniform motion. Graphing Motion Distance-Time Graphs is a visual representation of how the distance travelled by an object changes over time. It plots distance on the vertical axis (y-axis) and time on the horizontal axis (x-axis).To study the motion of an object we can draw a graph showing changes in distance with respect to time. The line in the middle represents Speed (gradient). We can match the graph with the picture bellow. Every 5 meter was made in 1 second Physics grade 9 LESSON 2 - Motion- Distance, Displacement, Speed, and Velocity Motion: Motion refers to a change in the position of an object over time relative to a reference point. Distance: Definition: The total length of the path traveled by an object, regardless of direction. Unit: Meters (m) scalar quantity Represented as x, d or s Example: If a car travels 50 meters north, then 30 meters south, the total distance traveled is 50 m + 30 m = 80 meters. Displacement: Definition: The shortest straight-line distance from the initial position to the final position, considering direction. Displacement is also a vector quantity. Measured in meter (m) Represented as x, d or s We can find the displacement of an object by subtracting the initial position from the final position: Combining displacement in one dimension If two or more displacements occur in a straight line (either along the x-axis or y-axis), you simply add or subtract them, depending on their direction. Same direction: Add the magnitudes. Opposite direction: Subtract the magnitudes. SPEED VS VELOCITY SPEED Definition: The rate at which an object covers distance. It does not take direction into account (a scalar quantity) Where: V is speed in m/s; X is distance in m and t is time taken in s Average Speed is defined as the total distance traveled divided by the total time taken to travel that distance. Example: If a car travels 100 meters in 20 seconds, its speed is: 5 m/s VELOCITY Definition: The rate at which an object changes its displacement (a vector quantity, meaning it includes both magnitude and direction). Where: V is velocity in m/s; X is displacement in m and t is time taken in s If the car’s displacement is 50 meters north in 20 seconds, the velocity is: 2.5 m/s If the car’s velocity is 50 m/s north in 10 seconds, its displacement is : 500 m Home work 5.1 Static Electricity Figure 5.2 What causes some objects to stick together when they come out of a clothes dryer? What other objects are affected by this sticking effect? It is a cold, dry winter day. You have just come home after playing your favourite winter sport, and you’re feeling chilled. You jump onto the couch and wrap yourself in a cozy blanket. You stare absently at the carpet on the floor as you try to get warm under the blanket. Maybe a snack would warm you up faster. You step into your slippers, walk across the carpet, and reach for the doorknob. Ouch! The shock is so strong that you can see a spark in the dimly lit room. The shocks you get from walking across a carpet and touching a metal doorknob look like tiny lightning bolts. In fact, that is exactly what they are! What could possibly be the same about a thunderstorm and walking across a carpet? How does rubbing create the condition that results in sparks? Charging Materials with Static Electricity In your Starting Point Activity, you rubbed a balloon against wool. Then you made it interact with your head, hand, and another balloon. When you rub different objects against each other, you change their properties and the way they behave. Sometimes the rubbed objects attract other objects. For instance, the rubbed balloon attracted your hair as you walked by it. Figure 5.2 shows ways that objects can attract each other after rubbing. Scientists use the word “charged” to talk about objects that attract or repel other objects. Some objects become charged when they are rubbed with other objects. The charges on a rubbed object are electrical. The build-up of charges is referred to as static electricity because the charges are on the surface of an object. (Static means “not moving.”) Describing How Charged Objects Behave Think again about what you observed in your Starting Point Activity. When you rubbed the balloon with wool cloth, you charged it with static electricity. After you charged the balloon, you saw that it behaved in certain ways.  When you moved toward the balloon, the balloon moved toward you. Charged objects can attract (pull on) other objects. Figure 5.3 shows an example of attracting. Figure 5.3 The charged comb is attracting bits of paper. Where have you seen an effect like this before? What do you think might cause it to happen?  When you put the charged balloon near a second charged balloon, the two charged balloons moved away from each other. Charged objects also can repel (push away) other objects. Figure 5.4 shows an example of repelling. Figure 5.4 This machine creates a strong static electric charge on its dome. Each strand of hair on this student’s head repels each of the other strands when she touches the charged dome. Is there a pattern to the way that objects behave when they are charged? When can you see objects repel? When can you see objects attract? You will explore more about how charged objects behave in Conduct an Investigation: Get Ready, Get Set, Charge! Types of Charges You have been collecting a lot of information about charged objects and static electricity. Think about what you have seen. For instance:  You have seen that two different charged objects can attract each other.  You have seen that two charged objects of the same kind can repel each other.  You have seen that a charged object can attract an object that is not charged (an uncharged object). Hundreds of years ago, scientists observed the same things about charged objects that you did. They concluded that there are two types of charge. They called one type of charge negative, and they used a minus sign (−) to refer to it. They called the other type of charge positive, and they used a plus sign (+) to refer to it. Objects that do not have a charge are called neutral. Figure 5.5 shows how you can use plus signs and minus signs to describe charged and uncharged objects.  A neutral object A.  six positive charges  six negative charges  number of positive charges equals number of negative charges  no overall charge An object with positive charge B.  nine positive charges  three negative charges  number of positive charges is greater than number of negative charges  overall positive charge An object with negative charge C.  four positive charges  eight negative charges  number of positive charges is less than number of negative charges  overall negative charge Figure 5.5 The charge that an object has depends on the balance between positive charges (plus signs) and negative charges (minus signs) in the object. How Charges Interact Two charges of the same type (both positive or both negative) are alike. They are called like charges. Two charges that are different (one type positive and one type negative) are not alike. They are called unlike charges. When charged objects and uncharged objects interact, there are three ways they can behave. These three ways are listed below and shown in Figure 5.6. 1. Unlike charges attract. 2. Like charges repel. 3. Charged objects attract uncharged (neutral) objects. Figure 5.6 Which of these photos shows like charges repelling? Which shows unlike charges attracting? Which shows a charged object attracting a neutral object? The Danger of Lightning A family was watching a thunderstorm from their front porch when their whole house was shaken by a blast. Lightning had struck their chimney, sending bricks falling to the ground. Charges travelled down the chimney pipe to the furnace, causing soot to shoot out into their home. Lightning strikes at two neighbouring homes passed through telephone and electrical lines, damaging phones, TVs, and computer equipment. How can lightning be such a destructive, natural event? Figure 5.7 An average bolt of lightning is about 10 km long. The temperature of the air near a lightning bolt can reach as high as 33 000°C! Scientists are still studying the mysteries of lightning. They believe that, during a thunderstorm, air currents cause water droplets and ice particles to collide and rub together inside a thundercloud. This action causes negative charges to move to the bottom of the cloud, while positive charges stay near the top. Static electricity is released, or discharged, in the form of lightning (Figure 5.8).  A B C  cloud and ground are neutral  strong negative charge from cloud repels negative  gigantic spark leaps from cloud to ground before the storm charges on Earth’s surface  many sparks travel between cloud and ground,  positive and negative charges  ground (and trees or buildings) under cloud appearing as a single flash of lightning are evenly mixed become positively charged Figure 5.8 Charges that build up during a thunderstorm are released as lightning. A lightning strike usually will take the shortest route between the negatively charged side of the cloud and the positively charged area of ground. This is the reason why lightning tends to strike tall buildings and trees. In the next activity, you will find out facts and fiction about lightning. You also will learn how to protect yourself from lightning. AT HOME ACTIVITYHow Shocking! You may have heard the saying “lightning never strikes twice in the same place.” Or maybe someone has told you that you can tell whether a thunderstorm is moving toward you or away from you just by listening to it. But are these ideas really true? In this activity, you will collect information about lightning and then sort fact from fiction. Some people try to protect themselves during a rain or lightning storm by taking cover under tall trees. Is this a good idea? What to Do 1. Talk with friends and members of your family to find out what they know and believe about lightning. Make a list of all the “facts” you hear from them. 2. Use library or Internet resources to investigate which of the statements on your list are true, and which are not. 3. As you do your research, add more statements to your list. Try to collect statements that are true and statements that are false. For every false statement you collect, write a true statement to correct it. What Did You Find Out? 1. How much of what you heard in the past about lightning was true? 2. Will any of the things you learned about lightning change how you and your family behave during a thunderstorm? Explain. 3. Using the information you have collected, prepare a poster or a presentation that will communicate accurate information about lightning. Include safety tips that will help people protect themselves from lightning both indoors and outdoors. 4. Share this information with your family and friends at home. 5.1 Summary You learned that rubbing together objects made of different materials can create a static electric charge on them. Since these charges stay in one place on the surface of the charged objects, they are referred to as static electricity. When charged objects and uncharged objects interact, one of three things can happen. 1. Unlike charges attract each other. 2. Like charges repel each other. 3. Charged objects attract uncharged objects. Lightning is a dangerous release of electricity that happens when charges build up in a thundercloud during a thunderstorm. Lightning tends to strike tall trees and buildings because the discharge usually takes the shortest route between the cloud and the ground. Check Your Understanding 1. The diagram shows the charge on three different objects, A, B, and C.  A B C a. Is object A positively charged, negatively charged, or uncharged? b. What will happen to object B if object C is brought close? c. What would have to be done to object C to make it uncharged? 2. You rub two identical wool cloths together, and then hold them close together (but not touching). What would you expect to observe? Explain. 3. a. Two balloons are hanging from the ceiling. The balloon on the left has the same charge as the balloon on the right. Draw how the balloons look. b. Two balloons are hanging from the ceiling. The balloon on the left has the opposite charge of the balloon on the right. Draw how the balloons look. c. Two balloons are hanging from the ceiling. The balloon on the left is charged. The balloon on the right is neutral. Draw how the balloons look. 4. Do you think it is safe to carry an umbrella during a lightn Static Electricity: When Electrical Charges Build Up on Objects Credit All matter contains tiny electric charges. The ground under your feet contains charges. So does the air around you and the clouds over your head. In fact, even you contain electric charges. Credit Everything contains electric charges⁠—⁠even you! How Charges Behave There are negative and positive electric charges. A neutral object has no overall electric charge. This is because a neutral object has equal numbers of negative and positive charges. Most objects are neutral. Credit How can you tell if this object is neutral? When two objects touch, a small number of electric charges can move from one object to the other. If two objects are rubbed together, more and more electric charges are transferred. The charges that move from one object to another are usually negative. One object loses negative charges and becomes positively charged. The other object gains negative charges and becomes negatively charged. This makes the charges opposite on the two objects. Static charge, or static electricity, occurs when electric charge builds up on an object. This becomes a charged object. Charged objects act in specific ways depending on their charge.  Like charges repel each other. This means that objects with like charges push each other away.  Opposite charges attract each other. In other words, objects with opposite charges stick to each other.  A charged object also attracts a neutral (uncharged) object. Get Instructions Credit  Identify which objects are positively charged, negatively charged, or neutral. How do you know? Explain why some objects attract each other but other objects repel each other. Have you ever seen clothes stick together when they come out of the dryer? They stick together because electric charges have built up on the clothes. How do you think the clothes became charged? This machine is called a Van de Graaff generator. It generates static electricity. When this student touches it, the static electricity causes their hair to stand on end. Why do you think this happens? Try ThisBe a Static Sleuth How can you generate static electricity? How do charged objects behave? Be a static sleuth in this activity to find out. Caution! Safety Needed Follow the instructions as well as other safety details your teacher provides.  Advise your teacher if you are allergic to feathers. Do not touch any of the materials if you are allergic to them.  Be careful when handling the balloons, to avoid popping them.  Handle all materials and equipment carefully.  Wash your hands when you finish the activity. Materials  two non-latex balloons  string  variety of testing materials provided by your teacher  copy of recording chart 1. Make or use a copy of this recording chart. For each test you complete in step 2, record your observations in the table. Activity Table Test number Objects tested Test method Observations Explanation for observations Intentionally empty Intentionally Intentionally Intentionally empty Intentionally empty empty empty Intentionally empty Intentionally Intentionally Intentionally empty Intentionally empty empty empty Intentionally empty Intentionally Intentionally Intentionally empty Intentionally empty empty empty Intentionally empty Intentionally Intentionally Intentionally empty Intentionally empty empty empty Intentionally empty Intentionally Intentionally Intentionally empty Intentionally empty empty empty Intentionally empty Intentionally Intentionally Intentionally empty Intentionally empty empty empty 2. Explore how a balloon acts when you rub it with different materials. o How can you make a balloon attract something else⁠—⁠in other words, bring something closer or stick to something? o How can you make two balloons repel or push each other away? (Hint: Hanging the balloons from string can help you test this.) o How do other materials behave when they are rubbed together? (Hint: Can you use them to attract or repel something?)  Student Check-In Choose the best answer. 1. How can you tell if an object is neutral? It has neither positive nor negative charges. It has an equal number of negative and positive charges. It has more positive than negative charges. It has more negative than positive charges. 2. What happens when two objects are rubbed together? Both objects become neutral. One object loses all positive charges to the other object. One object transfers negative charges to the other object. The two objects repel each other. Check Answers How did you make out? If you need to, now is a good time to go back and review any material. Checkpoint 1. What is static electricity? 2. The diagrams show the charge on three different objects. Identify which object is positively charged, which object is negatively charged, and which object is neutral. Credit 3. Two light objects are placed 2 cm apart on a smooth surface. One object is positively charged. The other object is negatively charged. Predict what will Static Electricity at Work Static electricity is not just something that makes your clothes stick together in an annoying way when they come out of the dryer. It is also working hard in the world around you. This video explores a few different devices that use static electricity. Media player Play Restart Rewind Forward Volume Slower Faster Hide captions  Show transcript Preferences Enter full screen 0:00 / 3:09Speed: 1xPaused Credit At the end of the video, you were asked to design a device or invention that uses static electricity to complete a task. Accept the challenge in the next activity! Try ThisStatic Electricity Engineering Project: Focus on STEM 1. Using words and drawings, design a device or invention that uses static electricity to complete a task. Here are a few points to keep in mind: o Remember that this is simply a design task. You do not have to build a model of your device or invention. o Your device or invention should use static electricity to complete at least one function. o The function should take advantage of the behaviour of electric charges.  Like charges repel or push each other away.  Opposite charges attract or stick to each other.  A charged object attracts a neutral (uncharged) object. 2. Once you have designed your device or invention, write up a brief explanation of how it works and what it is used for. Then share your explanation with your class. Electrical Charges Can Move through Some Materials Better than Others Credit Some materials let electric charges move through them easily. Other materials do not. A material that lets electric charges flow through it easily is called a conductor. Metals like copper, iron, and aluminum are good conductors. Electric charges at one end of a good conductor will spread through the whole object. A material that does not let electric charges flow through it easily is called an insulator. Most non-metals, like glass, plastic, and dry air, are good insulators. Electric charges at one end of a good insulator will generally stay put, rather than spreading through the whole object. Not all materials are good conductors or good insulators. Some materials let charges flow through them, but not that well. These materials are called fair conductors. Humid air is a fair conductor. So are sea water and tap water. Credit Static tends to build up when the air is dry, as it often is on a cold winter day. You are less likely to get a static shock on a day that is warm and humid. Why do you think this is the case? Try ThisConductivity Challenge Think you know a conductor from an insulator? Can you identify a fair conductor? In this activity, you will make educated guesses about which materials are good conductors, fair conductors, and good insulators. Then find out how you did by checking your answers. 1. Look at the photos. For each photo, record whether you think it is a good conductor, a fair conductor, or a good insulator. Explain why you made the choice you did. 2. Select the images to find out if you were right or wrong. Get Instructions Rubber is a good insulator. Enlarge Image Earth is a fair conductor. Enlarge Image Gold is a good conductor. Enlarge Image The human body is a fair conductor. Enlarge Image Wood is a good insulator. Enlarge Image Ceramic is a good insulator. Enlarge Image Steel is a good conductor. Enlarge Image Wool is a good insulator. Enlarge Image Lemon juice is a fair conductor. Enlarge Image Silicone is a good insulator. Enlarge Image Student Check-In  Choose the correct answer from the choices provided. 1. A good lets electric charges flow through it easily, and a good does not. 2. An example of a good conductor is. 3. Check Answers How did you make out? If you need to, now is a good time to go back and review any material. Checkpoint 1. Explain the difference between a conductor and an insulator. 2. Is it possible to create a static charge on a good conductor? Explain your reasoning. (Hint: Remember that a static charge is an electric charge that builds up on an object and generally stays in one place.) What Is Electricity? by Angela Lee Ask Questions Asking questions helps you think about what you are reading. You can ask questions to check your understanding. You can also use questions to evaluate a text’s message and to think beyond a text to new areas you can research. Electricity is a form of energy that we use daily. In fact, our world depends on it. Homes use electricity for heating, lighting, refrigerators, TVs, and every other gadget you can think of that plugs into an outlet or runs on batteries. Office buildings need electricity to run elevators, computers, and photocopiers. Hospitals are full of machines that require electricity, such as heartbeat and blood pressure monitors, and lasers used for surgery. How Do Machines Use Electricity? Most machines take electrical energy and transform it into other kinds of energy. For example, TVs and computers transform electrical energy into light (which makes the images you see on the screen or monitor), heat, and sound. In a blender or drill, electrical energy is transformed into motion, sound, and heat. Electricity also plays a role in machines that get power from other sources. A car engine runs on gasoline, but the car’s battery stores electricity that is used to create the sparks that start the gasoline burning. And the car’s headlights, turn signals, radio, and dashboard instruments also run on electrical energy from the battery. Making Light Before electricity, people used oil lamps or candles for light, and did little work after sunset. Today, electric lighting allows us to work or engage in recreational activities long into the night. How Does Electricity Travel? Most electricity is generated in power plants. High-power transmission lines on tall towers carry electricity to substations closer to where it will be used. From the substations, electricity is carried by overhead or underground wires to homes and businesses. Use questions to help you think beyond the text to new areas you can research. How does electricity get to your town pool or movie theatre? What Happens When You Flip the Switch? Wires throughout your home provide pathways for electricity to travel to different rooms. Light switches allow us to control the electricity used for overhead lighting. When a light switch is in the “off” position, it creates a gap in the pathway, or circuit, so electricity cannot travel to the light bulb. When you flip the switch to the “on” position, the gap is closed and electricity travels to the light bulb. The power switches on many electrical devices work in the same way. Conductors and Insulators Materials that electricity can travel through easily are called conductors. Wires made of solid metal are used in electrical devices because electricity can travel through metals easily. Materials that electricity does not travel through are called insulators. Wood, rubber, and most plastics are insulators. Many wires have a plastic covering that protects people from making contact with electricity, which can be harmful. Engineers and others who work with electricity wear rubber-soled shoes. It’s very dangerous if electricity passes through the body and into the ground. Rubber soles stop this from happening. Electrical workers keep power lines in good repair, so electricity can travel to your home. Rubber-soled shoes help protect against electrocution if a worker accidentally makes contact with electricity. Ask questions to check your understanding. How does knowing about conductors and insulators help you understand electrical safety rules? Reflect On Science 1. a. What are conductors and insulators? Give an example of each. b. Why is it important to coat wires used for electricity with an insulator? 2. a. What did people use before electricity to produce light? How were major tasks done? b. How do you think the use of electricity has changed your way of life? Credit 6.1 Using Electricity For an electric circuit to be useful, it must change electrical energy into another form of energy such as light, sound, or motion. You learned in 5 Investigating and Controlling Electricity that electricity flows in a circuit and produces a response in loads connected to the circuit. As charges pass through a load, electrical energy is converted into other forms of energy. But why does the electric current produce a different response in different kinds of loads? You will learn how some loads convert electrical energy. Figure 6.2 Compact fluorescent bulbs such as these use only one quarter to one third of the energy used by similar incandescent bulbs to produce the same amount of light. They are made to fit in the same light sockets as incandescent bulbs. Electricity to Light A light bulb is a device that turns electrical energy into heat and light energy. Traditional light bulbs, or incandescent bulbs, produce light by passing charges through a very thin wire, called a filament, inside the bulb. As charges pass through the wire, their electrical energy is given off as heat. As the wire heats up, it glows and produces light. As much as 95 percent of the energy used by an incandescent bulb is lost as heat. Compact fluorescent bulbs are designed in a different way. Charges pass through a tube containing mercury gas. As the charges collide with the gas, the mercury gives off energy that causes the coating of the tube to give off visible light. Only about 30 percent of the energy used by a compact fluorescent bulb is lost as heat. An LED (light-emitting diode) is a very efficient light source. LEDs use a type of fair conductor (also called a semiconductor) that produces light when an electric current runs through it. The majority of electrical energy that passes through an LED is converted into light and not heat. This means LEDs use less electricity to provide the same amount of light. They also last longer than incandescent and compact fluorescent bulbs. It takes 25 incandescent light bulbs to provide light for as long as a single LED! Electricity to Heat Inside a traditional light bulb, electricity is converted into heat. When the filament gets very hot, it glows, producing light. Many appliances produce heat alone, or with only a little light (think of the glow of the wires in a toaster). These loads work like the light bulb but use different materials so that the right amount of heat or light is produced. The heating filament in a toaster or hair dryer is made of a metal that becomes hot when an electric current runs through it. Figure 6.3 A traditional light bulb and a hair dryer work in a similar way. Electricity is converted to heat in both devices. However, in a light bulb we use the light produced by the glowing filament, and in a hair dryer we use the heat. Electricity to Magnetic Effects An electric current creates magnetic energy. The magnetic energy that surrounds a wire carrying a current is called a magnetic field. Magnets are objects that can attract some metals. You can use a small magnet to pick up paper clips or pins. You can create the same kind of magnetism in some metal objects by using electricity. Electromagnetism is the name given to magnetism produced by electricity. An electromagnet is a temporary magnet created by an electric current (Figure 6.4). In your next activity you will build your own electromagnet. Figure 6.4 Electromagnets are used at scrap yards and recycling centres to pick up metals and separate them from other materials. 6.1 Summary In this section, you learned that the passage of charges through a load in a circuit converts electrical energy into other forms of energy, such as light, heat, sound, or motion. You also learned about electricity and magnetism:  An electric current produces a magnetic field.  Electromagnetism is the magnetism produced by electricity.  An electric current will turn some metals into temporary magnets called electromagnets.  We can use electromagnets to convert electrical energy into motion. Check Your Understanding 1. Which part of an electric circuit converts electricity into other forms of energy? 2. How does a compact fluorescent bulb convert electricity into light? 3. What are the advantages of compact fluorescent bulbs or LEDs when compared to traditional (incandescent) bulbs? Can you think of any disadvantages of using compact fluorescent bulbs or LEDs? 4. What materials can be used to create an electromagnet? 5. What happens to the strength of an electromagnetic field when you increase the current flowing through a coil of wire around an iron bar? The illustration shows a simple electromagnet. Which part is missing? Physics grade 9 LESSON 1- Introduction to Physics (Motion) What is Physics Physics is the branch of science that deals with the study of matter, energy, and the laws of nature.  Matter is anything that has mass and takes up space. (books, paper, bags).  Energy The capacity or power to do work  laws of nature- study of natural processes (solar system, why fruits fall Importance of Physics:  It helps us understand how the universe works. Examples of Physics in Daily Life:  Gravity: Why objects fall when you drop them.  Motion: Cars moving on the road, people walking.  Electricity: Powering homes, computers, and phones.  Light and Sound: How we see things and how we hear sounds.  Branches of Physics (sub division)  Mechanics: The study of motion (moving cars, falling objects).  Thermodynamics: The study of heat and temperature (how a kettle boils).  Optics: The study of light (how mirrors and lenses work).  Electricity and Magnetism: The study of electric forces, circuits, and magnets ( powering devices, magnetic fields).  Waves and Sound: Understanding how sound and light travel (hearing music, seeing colors). What is Motion? Explain Motion: Motion is when something is moving. For example: ○ When you run, you are moving—so you're in motion. ○ When a ball rolls, it’s in motion. ○ Rest is when something isn’t moving, like a chair sitting still or a person sitting down. Homework: Ask students to observe 3 examples of motion in their daily life and explain the type of motion (e.g., a car driving, a clock ticking, or a swing moving). COMPLEXO ESCOLAR PRIVADO INTERNACIONAL CEPI 2024-2025 ACADEMIC YEAR MIDTERM ASSESSMENT PREPARATION QUIZ – MOTION NAME: ____________________________________ CLASS: 9_____________ 1. What is the SI unit of speed? o a) Meter b) Second c) Meter per second (m/s) d) Kilometer o 2. Which of the following is a scalar quantity? o a) Velocity b) Displacement c) Acceleration d) Speed o 3. Which of the following describes the rate of change of velocity? o a) Speed b) Acceleration c) Force d) Distance o 4. If a car travels 150 meters in 5 seconds, what is its average speed? o a) 25 m/s b) 30 m/s c) 20 m/s d) 15 m/s True or False 6. Displacement can never be greater than the distance travelled. TRUE OR FALSE 7. A body in uniform motion has zero acceleration. TRUE OR FALSE 8. A moving object has zero momentum. TRUE OR FALSE 9. Define displacement. How is it different from distance? 10. What is the difference between speed and velocity? Give an example. 11. A cyclist covers a distance of 60 meters in 3 seconds. Calculate their average velocity if they move in a straight line. 12. If a car moves with a constant velocity, its acceleration is __________. 13. The area under a velocity-time graph represents the __________ covered by the object. 14. The total path covered by a moving object is called its __________, while the shortest straight line between the start and end points is called its __________. 15. A car starts from rest and accelerates uniformly to a velocity of 15 m/s in 6 seconds. What is the distance covered by the car during this time? 16. A car travels 150 kilometers in 3 hours. What is its speed? 17. A person runs 400 meters in 50 seconds. What is their speed? 18. If a cyclist travels 90 meters in 10 seconds, what is their speed? 19. A bus covers 60 kilometers in 1.5 hours. Calculate its speed. 20. A plane flies 1,200 kilometers in 2 hours. What is its speed? 21. A car travels at a speed of 50 km/h for 4 hours. How far does it travel? 22. A car is moving at a speed of 60 km/h. How long will it take to travel 180 kilometers? 23. If a cyclist rides at 12 m/s, how much time will they take to cover 600 meters? 24. A train is traveling at a speed of 90 km/h. How long will it take to cover a distance of 270 kilometers? 25. What is the velocity of an object that travels 500 meters north in 10 seconds? a) 50 m/s b) 500 m/s c) 5 m/s north d) 50 m/s north