Forces The Nature of Force Friction and Gravity Newton’s First and Second Laws Newton’s Third Law Rockets and Satellites Table of Contents.

Slides:



Advertisements
Similar presentations
The Nature of Force Chapter 10 section 1.
Advertisements

FORCES Mrs. Cholak.
FORCE Chapter 10 Text. Force A push or a pull in a certain direction SI Unit = Newton (N)
Forces.
What are Forces?. What are forces? A force is a push or a pull. We learned that Newton’s 2 nd Law states that a Force is equal to the mass of a moving.
Table of Contents Chapter Preview 10.1 The Nature of Force
Pearson Prentice Hall Physical Science: Concepts in Action
Studying the Force of Gravity
Forces 1 Dynamics FORCEMAN. What causes things to move? Forces What is a force? –A push or a pull that one body exerts on another. 2.
Chapter 3 Forces.
Forces 1 Dynamics FORCEMAN. What causes things to move? Forces What is a force? A push or a pull that one body exerts on another. 2.
Chapter 10.
Combining Forces - The Nature of Force
What are Forces? A force is a push or a pull on an object.
Newton’s 1st Law of Motion
Forces The Nature of Force Friction and Gravity Newton’s First and Second Laws Newton’s Third Law Rockets and Satellites Table of Contents.
Chapter 3 Forces.
Resistance of an object to a change in its motion inertia.
The Nature of Force Chapter 3 section 4 What is a force Force is a push or pull. Forces are either balanced or unbalanced.
Forces Chapter Force and Acceleration The acceleration experienced by an object is directly proportional to the force exerted on it. The acceleration.
Chapter 10 Forces Objects will not begin to move or change motion until an unbalanced force acts on it. Newton’s 1st Law of Motion Inertia All mass resists.
Forces & Motion Chapter 12.  Newton ’ s first law of motion - an object at rest remains at rest and an object in motion maintains its velocity unless.
Chapter 12.  Newton ’ s first law of motion - an object at rest remains at rest and an object in motion maintains its velocity unless it experiences.
Chapter: Force and Newton’s Laws
All forces that affect motion.
< BackNext >PreviewMain Chapter 13 Forces and Motion Preview Section 1 Gravity: A Force of AttractionGravity: A Force of Attraction Section 2 Gravity and.
1 Chapter 10-Forces All forces that affect motion.
Section 1 The Nature of Force
What are Forces?. Force a push or a pull a force gives energy to an object causing it to… –start moving, stop moving, or change direction the unit of.
Forces and Motion Chapter 12.
Force = a push or a pull Mrs. Clarici
Chapter 2 Forces Acceleration; Friction; Gravity; Momentum; Newton’s 1st, 2nd, and 3rd Laws.
Newton’s first law of motion states that an object will remain at rest or moving at a constant velocity unless it is acted upon by an unbalanced force.
Forces & Motion. What is a Force? Force: push or pull Unit: Newton (N)  Kg x m/s 2 Vector: has both magnitude & direction.
Forces. I. Section 1 A. Newton- (N) the SI unit for the magnitude of a force. Also called weight. B. Force- a push or a pull. Described by its magnitude.
Forces Motion and Forces. Forces What is a force? A force is a push or pull. What happens when forces combine? Forces combine to produce a net force.
Chapter 3. Force, Mass, and Acceleration Newton’s first law of motion states that the motion of an object changes only if an unbalanced force acts on.
Forces. Force is a push or a pull. is a push or a pull. a force is described by its strength and by the direction in which it acts. a force is described.
Describing and Measuring Motion Are you in motion right now? Motion: an object is in motion if the distance from another object is changing.
Forces  A force is a PUSH or a PULL.  Described by: 1. Its strength 2. The direction in which it acts  Measured in: Newtons (N)  Measured by: Spring.
Resources Section 1 Laws of Motion Objectives Identify the law that says that objects change their motion only when a net force is applied. Relate the.
CHAPTER 10 THE NATURE OF FORCE.
Forces The Nature of Force Friction and Gravity Newton’s First and Second Laws Newton’s Third Law Rockets and Satellites Table of Contents.
Forces The Nature of Force Friction and Gravity Newton’s First and Second Laws Newton’s Third Law Rockets and Satellites Table of Contents.
Forces and Motion CHAPTER 6. Gravity and Motion Aristotle (round 400 BC) believed that heavier objects fell to the earth faster than lighter objects.
ESSENTIAL QUESTIONS: WHAT ARE NEWTON’S 3 LAWS OF MOTION? HOW DO THESE LAWS APPLY TO REAL-LIFE SITUATIONS? Forces & Motion.
The Nature of Force and Motion 1.Force – A push or a pull – How strong it is and in what direction? 2.Net Force – The sum of all forces acting on an object.
Forces The slope is 9.8. The speed increases by 9.8 m/s each second. Calculating: Calculate the slope of the graph. What does the slope tell you about.
Forces FORCEMAN.
Forces and Motion Study Guide
Chapter 10 Forces. Chapter 10 Forces (10.1) The Nature of Force GOAL: To understand how force is distributed, and how forces act on one another. VOCABULARY.
CHAPTER 10 THE NATURE OF FORCE.
Forces FORCEMAN.
Chapter 12: ALL ABOUT MOTION
Forces.
Unit 2 – Forces and Energy
Laws of Motion Chapter Two.
Forces Unit Note-Taking.
Chapter 10 Vocab Review 8th Grade.
Forces and Motion Study Guide
Forces and Motion Study Guide
Section 1: Newton’s First and Second Laws
Forces.
Forces.
Chapter 13 Preview Section 1 Gravity: A Force of Attraction
Table of Contents The Nature of Force Friction and Gravity
Table of Contents The Nature of Force Friction and Gravity
Forces.
Force and Newton’s Laws of Motion
Force A force is a pull or a push..
Presentation transcript:

Forces The Nature of Force Friction and Gravity Newton’s First and Second Laws Newton’s Third Law Rockets and Satellites Table of Contents

Forces Force A force is simply a push or a pull. Isaac Newton accurately described the force of all moving objects in 1687 when he published his thesis. We still use these laws as the basis of all physics to this day.

Forces Units of Force When describing the strength of a force we use the SI unit of Newtons (N) The newton is the SI unit for force; it is equal to the amount of net force required to accelerate a mass of one kilogram at a rate of one meter per second squared. F = ma: or multiplying mass (kg) by acceleration (m/s 2 ) Therefore:1 N = 1 kg·m/s 2

Forces Real World Examples of the Newton 1 N is the force of Earth's gravity on a mass of about 102 g or roughly the mass of a small apple On Earth's surface, a mass of 1 kg exerts a force of approximately 9.8 N [down] (or 1.0 kilogram-force; 1 kgf= N by definition) The force of Earth's gravity on a human being with a mass of 70 kg is approximately 686 N It is common to see forces expressed in kilonewtons or kN (1 kN = 1,000 N)

Forces - The Nature of Force Combining Forces The net force determines whether an object moves and also the direction it will move! The combination of all forces acting on an object is called the net force.

Forces - The Nature of Force Unbalanced Forces Unbalanced forces acting on an object result in a net force and cause a change in the object’s motion.

Forces - The Nature of Force Balanced Forces Balanced forces acting on an object do not change the object’s motion.

Forces Asking Questions Before you read, preview the red headings. In a graphic organizer like the one below, ask a what or how question for each heading. As you read, write answers to your questions. What is a force? A force is a push or pull. What happens when forces combine? Forces combine to produce a net force. Question Answer - The Nature of Force

Forces End of Section: The Nature of Force

Forces Friction Friction is the force that is exerted on two surfaces as they rub against one another. The strength of the friction force depends on two things: 1.How hard the surfaces are pushed together 2.What material the surface is made of

Forces Types of Friction 1.Static friction acts on objects that are at rest 2.Sliding friction occurs when two solid surfaces slide past one another 3.Rolling friction occurs when an object rolls across a surface 4.Fluid friction occurs when a solid object moves through a fluid

Forces What type of friction is occuring?

Forces What type of friction is occurring?

Forces Compare and Contrast

Forces What type of friction is occurring?

Forces What type of friction is occurring?

Forces How were the Egyptian Pyramids Built?

Forces Gravity Gravity is a force that pulls objects toward one another Gravity keeps objects in place unless they are acted on by an outside force! Sir Isaac Newton accurately described this in his law of universal gravitation Gravity acts on all objects regardless of their size and or location in the universe This means that all objects are attracted to one another but there are some rules involved in how much attraction occurs This is mostly due to differences in mass What is the difference between mass and weight? Mass is the amount of matter in an object. Weight is the measure of gravitational force on an object.

Forces - Friction and Gravity Gravity Two factors affect the gravitational attraction between objects: mass and distance.

Forces - Friction and Gravity Gravity The force of gravity on a person or object at the surface of a planet is known as weight. Can you find anything wrong with this picture?

Forces Gravity and Motion An object is said to be in free fall when gravity is the only force acting on it. This results in an unbalanced force and causes the object to accelerate in a downward motion at 9.8m/s This acceleration is not dependent on mass! Air resistance is fluid friction that acts in the opposite direction to motion Air resistance is not the same for all objects! Terminal velocity occurs when the force of air resistance equals the weight of the object. *Therefore the object will continue to fall with a constant velocity but with no acceleration!

Forces Free Fall Use the graph to answer the following questions. - Friction and Gravity

Forces Free Fall Time is on the horizontal axis, and speed is on the vertical axis. Interpreting Graphs: What variable is on the horizontal axis? The vertical axis? - Friction and Gravity

Forces Free Fall The slope is 9.8. The speed increases by 9.8 m/s each second. Calculating: Calculate the slope of the graph. What does the slope tell you about the object’s motion? - Friction and Gravity

Forces Free Fall 58.8 m/s Predicting: What will the speed of the object be at 6 seconds? - Friction and Gravity

Forces Free Fall The speed values would not change. Drawing Conclusions: Suppose another object of the same size but with a greater mass was dropped instead. How would the speed values change? - Friction and Gravity

Forces - Friction and Gravity Air Resistance Falling objects with a greater surface area experience more air resistance!

Forces Projectile Motion A projectile is any object projected into space by the exertion of a force. Horizontal velocity does not affect how fast an object will fall! Therefore, both the red and yellow ball will hit the ground at the same time On our planet, all objects are accelerated by the force of gravity (9.8m/s) towards the center of the earth.

Forces What is going on in this diagram?

Forces FrictionGravity Comparing and Contrasting As you read, compare and contrast friction and gravity by completing a table like the one below. Effect on motion Opposes motion Pulls objects toward one another Depends on Types of surfaces involved, how hard the surfaces push together Mass and distance Measured inNewtons - Friction and Gravity

Forces End of Section: Friction and Gravity

Forces Newton’s First Law of Motion An object at rest will remain at rest & An object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force *Gravity and friction are both unbalanced forces that work together to change an object’s motion

Forces Inertia Newton’s first law is also called the Law of Inertia Inertia refers to an object’s resistance to change in motion Inertia depends on mass! The greater the mass of an object, the greater its inertia and the greater the force required to change the object’s motion

Forces Inertia

Forces Inertia

Forces Newton’s Second Law of Motion Second law: The acceleration (a) of an object is directly proportional to the net force (F) and inversely proportional to the mass (m) F = maorAcceleration = Net Force/Mass Recall acceleration is measured in meters per second per second & Mass is measured in Kilograms *Force is measured in Newtons (N) or Kg x m/s 2

Forces Describe the following picture

Forces Compare and Contrast

Forces How is this picture different?

Forces Changes in Force and Mass F = maorAcceleration = Net Force/Mass You can increase the acceleration of an object by changing the force or mass of the object If you increase the force you will increase the acceleration If you decrease the force you will decrease the acceleration *Force and acceleration are directly proportional! If you increase the mass then acceleration will decrease if the force remains constant If you decrease the mass then acceleration will increase if the force remains constant *Acceleration and mass are inversely proportional!

Forces Calculating Force A speedboat pulls a 55-kg water-skier. The force causes the skier to accelerate at 2.0 m/s 2. Calculate the net force that causes this acceleration. Read and Understand What information have you been given? Mass of the water-skier (m) = 55 kg Acceleration of the water-skier (a) = 2.0 m/s 2 - Newton’s First and Second Laws

Forces Calculating Force A speedboat pulls a 55-kg water-skier. The force causes the skier to accelerate at 2.0 m/s 2. Calculate the net force that causes this acceleration. Plan and Solve What quantity are you trying to calculate? The net force (F net ) = __ What formula contains the given quantities and the unknown quantity? a = F net /m or F net = m X a Perform the calculation. F net = m X a = 55 kg X 2.0 m/s 2 F = 110 kg m/s 2 F = 110 N - Newton’s First and Second Laws

Forces Calculating Force A speedboat pulls a 55-kg water-skier. The force causes the skier to accelerate at 2.0 m/s 2. Calculate the net force that causes this acceleration. Look Back and Check Does your answer make sense? A net force of 110 N is required to accelerate the water-skier. This may not seem like enough force, but it does not include the force of the speedboat's pull that overcomes friction. - Newton’s First and Second Laws

Forces Calculating Force Practice Problem What is the net force on a 1,000-kg object accelerating at 3 m/s 2 ? 3,000 N (1,000 kg X 3 m/s 2 ) - Newton’s First and Second Laws

Forces Calculating Force Practice Problem What net force is needed to accelerate a 25-kg cart at 14 m/s 2 ? 350 N (25 kg X 14 m/s 2 ) - Newton’s First and Second Laws

Forces Outlining As you read, make an outline about Newton’s first and second laws. Use the red headings for the main topics and the blue headings for the subtopics. Newton’s First and Second Laws I.Newton’s First Law of Motion A.Inertia B.Inertia Depends on Mass II.The Second Law of Motion A.Changes in Force and Mass - Newton’s First and Second Laws

Forces End of Section: Newton’s First and Second Laws

Forces Newton’s Third Law of Motion “If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object” or “For every action there is an equal but opposite reaction” *Acting forces encounter other forces in the opposite direction *Forces are found in pairs…therefore we refer to this relationship as action-reaction forces

Forces Newton’s Third Law Action-reaction pair examples: *Not always easy to detect! Action-reaction forces can act on the same object or different objects If action-reaction forces act on the same object they can cancel each other out Action-reaction forces will not cancel each other if they act on different objects!

Forces Newton’s Third Law of Motion The law of conservation of momentum: The total momentum of any group of objects remains the same, or is conserved, unless outside forces act on the objects. Momentum is related to an objects mass and velocity Momentum = Mass x Velocity Where mass is measured in kg and velocity in m/s The momentum of an object is in the same direction as its velocity The more momentum an object has, the more difficult it is to stop! Again, friction and gravity example of an outside force!

Forces Calculating Momentum Which has more momentum: a 3.0-kg sledgehammer swung at 1.5 m/s or a 4.0-kg sledgehammer swung at 0.9 m/s? Read and Understand What information have you been given? Mass of smaller sledgehammer = 3.0 kg Velocity of smaller sledgehammer = 1.5 m/s Mass of larger sledgehammer = 4.0 kg Velocity of larger sledgehammer = 0.9 m/s - Newton’s Third Law

Forces Calculating Momentum Which has more momentum: a 3.0-kg sledgehammer swung at 1.5 m/s or a 4.0-kg sledgehammer swung at 0.9 m/s? Plan and Solve What quantities are you trying to calculate? The momentum of each sledgehammer = __ What formula contains the given quantities and the unknown quantity? Momentum = Mass X Velocity Perform the calculation. Smaller sledgehammer = 3.0 km X 1.5 m/s = 4.5 kgm/s Smaller sledgehammer = 4.0 km X 0.9 m/s = 3.6 kgm/s - Newton’s Third Law

Forces Calculating Momentum Which has more momentum: a 3.0-kg sledgehammer swung at 1.5 m/s or a 4.0-kg sledgehammer swung at 0.9 m/s? Look Back and Check Does your answer make sense? The 3.0-kg hammer has more momentum than the 4.0-kg one. This answer makes sense because the 3.0-kg hammer is swung at a greater velocity. - Newton’s Third Law

Forces Calculating Momentum Practice Problem A golf ball travels at 16 m/s, while a baseball moves at 7 m/s. The mass of the golf ball is kg and the mass of the baseball is 0.14 kg. Which has the greater momentum? Golf ball: kg X 16 m/s = 0.72 kgm/s Baseball: 0.14 kg X 7 m/s = 0.98 kgm/s The baseball has greater momentum. - Newton’s Third Law

Forces Calculating Momentum Practice Problem What is the momentum of a bird with a mass of kg flying at 15 m/s? 0.27 kgm/s (0.018 kg X 15 m/s = 0.27 kgm/s) - Newton’s Third Law

Forces - Conservation of Momentum In the absence of friction, momentum is conserved when two train cars collide. - Newton’s Third Law

Forces Previewing Visuals Before you read, preview Figure 18. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions. Conservation of Momentum Q. What happens when two moving objects collide? A. In the absence of friction, the total momentum is the same before and after the collision. Q. What is the momentum of an object? A. Its mass multiplied by its velocity - Newton’s Third Law

Forces End of Section: Newton’s Third Law

Forces - Rockets and Satellites What Is a Satellite? A projectile follows a curved path because the horizontal and vertical motions combine.

Forces - Rockets and Satellites What Is a Satellite? A satellite is any object that orbits another object in space.

Forces - Rockets and Satellites What Is a Satellite? Any force that causes an object to move in a circular path is a centripetal force. Centripetal means center seeking.

Forces - Rockets and Satellites What Is a Satellite? The faster a projectile is thrown, the father it travels before it hits the ground. A projectile with enough velocity moves in a circular orbit.

Forces - Rockets and Satellites What Is a Satellite? Depending on their uses, artificial satellites orbit at different heights.

Forces Main Idea Detail Identifying Main Ideas As you read the section “What Is a Satellite?” write the main idea in a graphic organizer like the one below. Then write three supporting details that further explain the main idea. A satellite stays in orbit due to… its inertiaEarth’s gravityEarth’s shape - Rockets and Satellites

Forces End of Section: Rockets and Satellites

Forces Graphic Organizer Friction between an unmoving book and desk Type of Friction Static Occurs WhenExample Sliding Rolling Fluid An object is not moving Two solid surfaces slide over each other Rubber pads on a bicycle’s brakes An object rolls across a surface Ball bearings in skateboard wheels A solid object moves through a fluid Air resistance

Forces End of Section: Graphic Organizer