CHAPTER 5: MATTER IN MOTION
Chapter 5 basically teaches you about how you measure motion matter through speed, and how you can measure the average speed of matter moving through motion.
SECTION 1: MEASURING MOTION
VOCABULARY
1. Motion: An objects change in position relative to a reference point
2. Speed: the distance traveled divided by the time interval during which the motion occurred
3. velocity: the speed of an object in a particular direction
4. acceleration: the rate at which velocity changes overtime; an object accelerates if its speed, direction, or both change
1. Motion: An objects change in position relative to a reference point
2. Speed: the distance traveled divided by the time interval during which the motion occurred
3. velocity: the speed of an object in a particular direction
4. acceleration: the rate at which velocity changes overtime; an object accelerates if its speed, direction, or both change
SUMMARY
In the first section of chapter 5 , section 1 talked about how to measure motion through reference points, determining average speed, velocity and acceleration. Some common reference points include non moving objects like trees or buildings. You determine the average speed by dividing total distance by time. An example would be 360km/4h. The velocity of an object is the speed of an object in a particular direction. An object's velocity changes if either its speed or direction changes. Accerlaration is the rate to which velocity changes, an increase in velocity is commonly called positive acceleration. A decrease in acceleration is called negative acceleration or deceleration. You can caculate the average acceleration by dividing the final velocity-starting velocity, by the time it takes to change velocity. Centripetal acceleration occurs on a ferris wheel at an amusent park.
Velocity and acceleration
In this picture shows velocity and acceleration in motion.
Section 2: What Is a force?
VOCABULARY
1. Force: a push or a pull exerted on an object in order to change the motion of the object ; force has size and direction
2. newton: the si unit for force (symbol,N)
3..net force: the combination of all of the forces acting on an object
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2. newton: the si unit for force (symbol,N)
3..net force: the combination of all of the forces acting on an object
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SUMMERY OF SECTION 2
In section 2 of chapter 5 talked about force, forces acting on objects, net force, balanced, and unbalanced forces.A force is the a push or pull exerted on an object, so all forces act on an object. For any push to occur, something has to recieve the push or pull. An example of a force that you cannot see is gravity and wind. Net force is combination all of the forces acting on an object. To determine net force, because the forces act in the same direction. A balanced force is a force that has a net force of 0 n. Balanced forces will not cause a change in the motion of a moving object. An example of balanced forces include a chair on the ground or a book on a table. An unbalanced force is an object with not 0 N. Unbalanced forces produce a change in motion. Unbalanced forces are necessary to cause a non-moving object to start moving. An example of an unbalanced force is an moving soccer ball or a moving car.
UNBALANCED FORCES
This picture shows unbalanced forces, because the people on the left are using more force than the right side.
SECTION 3: FRICTION: A FORCE THAT OPPOSES MOTION
VOCABULARY
1.Friction: a force that opposes motion between two surfaces that are in contact
SUMMERY
In section 3 of chapter 5 it talks about the source of friction, the effect of force on friction, types of friction, and ways to reduce and increase friction. Friction occurs because the surface of any object is rough. The amount of friction between two surfaces depends on many factors. The two factors include the force pushing the surfaces together and the roughness of the surfaces. The amount of friction depends on the force pushing the surfaces together. If this force increases, the hills and valleys of the surfaces can come into closer contact. Objects that weigh less exert less downward force than objects that weigh more do. There are two types of friction kinetic and static friction. Kinetic friction is the movement between surfaces. The amount of kinetic friction between two surfaces depends on how the surfaces move. Some examples of kinetic friction include scratching yourself or using a pencil. Static friction is when a force is applied to an object but does not cause the object to move. Static friction can be overcome by applying a large enough force.
SECTION 4: GRAVITY: A FORCE OF ATTRACTION
VOCABULARY
1. GRAVITY: A force of attraction between objects that is due to their masses
2. WEIGHT: a measure of the gravitational force exerted on an object its value can change with the location of the object in the universe.
3. mass: a measure of the amount of matter in an object
2. WEIGHT: a measure of the gravitational force exerted on an object its value can change with the location of the object in the universe.
3. mass: a measure of the amount of matter in an object
SUMMARY
Section 4 explains what is gravity, and how it affects all objects on earth and in space. All matter has mass,gravity is a result of mass. That is the reason matter is affected by gravity. In 1665 the British scientist Sir Isaac Newton came up with the idea. Newton summarized his ideas about gravity in a law now known as the law of universal gravitation. All objects in the universe attract each other through gravitational force. In the law of universal gravitation, gravitational force increases as mass increases. What this means is that the bigger the objects mass the more force acts on it. Part two of the law explains that when an object moves farther away from a gravitational force, the gravitational force decreases in strength. Mass is the measure of the amount matter in an object, but weight is the measure of the amount of gravitational force on an object. The SI unit of force is usually measured in a newton. The SI unit of mass is measured in kilograms.
gravitational force at work
In this picture shows how strong the gravitational force of the Sun is. click here for more info on section 5