Forces and the Laws of Motion

Slides:



Advertisements
Similar presentations
Forces – Chapter 4.
Advertisements

Force/Newton’s First Law Notes
Ch. 8.3 Newton’s Laws of Motion
FORCES Mrs. Cholak.
Forces and Newton’s 3 Laws of Motion Robert Strawn Compiled 10/16/11.
Physics Exploring Newton’s Laws of Motion. Newton’s First Law of Motion  Inertia  A body in motion tends to stay in motion unless acted upon by an outside.
& ForcesForces. inertia the tendency of an object to resist any change in its motion Inertia is a property of matter and does not depend on the position.
Ch 4 – Forces and the Laws of Motion. What is a force? A force is a push or pull A force causing a change in velocity –An object from rest starts moving.
Chapter 4 Newton’s First Law of Motion: Inertia. Newton’s First Law - Inertia In Fancy Terms: Every object continues in a state of rest, or of motion.
Welcome to Physical Science. Inertia The Tendency of things to resist changes in motion.
Newton’s Laws.
Chapter 4 The Laws of Motion. Forces Usually think of a force as a push or pull Usually think of a force as a push or pull Vector quantity Vector quantity.
Chapter 5 The Laws of Motion. Forces Usually think of a force as a push or pull Usually think of a force as a push or pull Vector quantity Vector quantity.
Newton’s Second and Third Laws
Ch. 4 Forces and Laws of Motion
Chapter 4 Physics. Section 4-1 I. Forces A. Def- a push or pull; the cause of acceleration. B. Unit: Newton Def- amt. of force when acting on a 1 kg mass.
Chapter 4 The Laws of Motion. Classical Mechanics Describes the relationship between the motion of objects in our everyday world and the forces acting.
S-24 Define the following terms A. Weight B. Gravity C. Friction
Force A push or pull exerted on an object..
Forces in 1 Dimension Chapter Force and Motion Force is push or pull exerted on object Forces change motion –Makes it important to know the forces.
Dynamics: The Why of Motion Inertia, Force, and Newton’s Laws.
Forces and the Laws of Motion Chapter Changes in Motion Objectives  Describe how force affects the motion of an object  Interpret and construct.
Forces and the Laws of Motion
Unit 1 B Newton's Laws of Motion. 2 Classical Mechanics Describes the relationship between the motion of objects in our everyday world and the forces.
Honors Physics Newton’s First and Third Laws of Motion.
In order to change the motion Of an object, you must apply A force to it.
Sir Isaac Newton Newton’s Laws of Motion Newton’s 1st Law of Motion -An object at rest, will remain at rest, unless acted upon by an unbalanced.
 Define the following terms  A. Weight  B. Gravity  C. Friction S-33 I can explain the relationship between weight, gravity, and friction.
Chapters 5-6 Test Review Forces & Motion Forces  “a push or a pull”  A force can start an object in motion or change the motion of an object.  A force.
LAWS OF MOTION.
Physics Chapter 4. Chapter Forces Force - any kind of push or pull on an object –Ex. Hammer, wind, gravity, bat Measuring force –Spring scale Force.
Newton’s 1 st Law Inertia. Force Anything capable of changing an object’s state of motion Any push or pull Causes object to speed up, slow down, or change.
Force and Motion. Force Push or pull on an object.
If you could kick the person in the pants responsible for most of your trouble, you wouldn't sit for a month. Theodore Roosevelt.
Motion & Forces.
Chapter 4 Newton’s First Law of Motion: Inertia. Newton’s First Law - Inertia In Fancy Terms: Every object continues in a state of rest, or of motion.
Newton’s Second and Third Laws Chapter 4 Section 3.
Newton’s Laws AP Physics C. Basic Definitions  Inertia  property of matter that resists changes in its motion.  Mass  measurement of inertia  Force.
& ForcesForces. Isaac Newton Isaac Newton (1642–1727) Isaac Newton proposed that the tendency of an object was to maintain in its current state of motion.
Dynamics!.
Forces and the Laws of Motion Chapter 4. Forces and the Laws of Motion 4.1 Changes in Motion –Forces are pushes or pullss can cause acceleration. are.
Forces & Motion. Motion A change in the position of an object Caused by force (a push or pull)
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.
1 Physics: Chapter 4 Forces & the Laws of Motion Topics:4-1 Changes in Motion 4-2 Newton’s First Law 4-3 Newton’s Second & Third Laws 4-4 Everyday Forces.
Physics Section 4.2 Apply Newton’s 1st Law of Motion Newton’s 1 st Law of Motion (Law of Inertia) An object at rest remains at rest and an object in motion.
Chapter 4 Forces in One Dimension. Classical Mechanics Describes the relationship between the motion of objects in our everyday world and the forces acting.
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.
Newton’s First Law of Motion
Newton’s Laws.
Forces change Motion.
FORCE A force is any influence that can change the velocity of a body. Forces can act either through the physical contact of two objects (contact forces:
Newton’s Laws.
Motion & Forces.
Newton’s First Law of Motion
Newton’s 3rd law.
Forces.
Chapter 4 Forces.
Chapter 4 The Laws of Motion.
Newton’s Laws of Motion
Sir Isaac Newton
Newton’s Laws of Motion Chapters 2,3,6,7
Connecting Motion with Forces
Forces.
Forces and Newton’s Laws of Motion
Newton’s Laws of Motion
Chapter 6 – Action and Reaction
Forces and Motion Ch. 12 Intro to Physics.
Force A push or pull exerted on an object..
Force.
Ch.4 Newton's Laws of Motion & Net Forces.
Presentation transcript:

Forces and the Laws of Motion Chapter 5

Force A push or a pull, or any action that has the ability to change an object’s motion. The SI unit of force is Newtons (N).

3 Ways a Force Changes Motion 1. Increase the speed of an object 2. Decrease the speed of an object 3. Change the direction in which an object is moving

Force A force does not necessarily have to change the motion, but it must have the ability to do so. Example: Push down on a table. Conversely, there can be no change in motion without also having a force.

Forces can act through a contact or at a distance. Contact force: A force that arises from the physical contact of 2 objects. Field force: This force does not involve physical contact between 2 objects. For example: the attraction or repulsion between electrical charge, gravity (Demos)

Four Fundamental Forces of the Universe Gravity Electricity/ Magnetism Strong Weak (videos)

Newton’s First Law “An object at rest remains at rest, and an object in motion continues in motion unless the object experiences a net external force.” The tendency of an object to resist changing its state of motion is called inertia. Newton’s 1st Law is also called the Law of Inertia.

Inertia All objects have mass. All objects have/or exhibit inertia. What about satellites? What about rainbows? All objects have mass. What is mass? Unit for mass? All objects have/or exhibit inertia. Inertia is an inherent property of matter, just like gravity. What about clouds? What about lizards?

Inertia is a Property of Mass The amount of inertia an object has depends on its mass. More mass = more inertia = requires more force to overcome inertia

Net Force If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another depending on their direction and magnitude. Unbalanced forces will cause changes in speed or direction of an object’s motion.

Free Body Diagrams A diagram of an object which includes only the forces exerted on the object. A force has both magnitude (a size like 5N or 10N) and a direction (an arrow showing the direction the force is pushing or pulling). FBDs help us visualize the situation and keep track of how the forces are acting.

Knowledge to Review Acceleration = Δv/Δt = (vf-vi)/Δt Motion of an object with constant acceleration (kinematics notes) Constant velocity means ZERO acceleration

Newton’s 2nd Law Force is proportional to mass and acceleration. The acceleration of an object is directly proportional to the net external force acting on the object and inversely proportional to the object’s mass. (Law of Force) ΣF = ma (or a = F/m) Net external force = mass x acceleration

Newton’s 2nd Law cont’d 𝐹 =𝑚 𝑎 𝑛𝑒𝑡 This means “the sum of all the forces acting on an object are equivalent to that object’s mass times it’s net acceleration.” Can also rewrite or expand like this: 𝐹 1 + 𝐹 2 + 𝐹 3 … =𝑚 𝑎 𝑛𝑒𝑡 Remember! Forces are vectors and direction matters.

Newton’s 3rd Law “For every action there is an equal and opposite reaction.” Forces occur in pairs because forces arise from the interaction of at least two objects. Ex: - the Earth pulls on you and you pull on the Earth - you push on a wall and the wall pushes back on you - a bird’s wing pushes on the surrounding air and the air pushes back

Newton’s 3rd Law If all forces occur in pairs, and are equal and opposite, why don’t all forces just cancel out? Because the paired forces occur on different objects. You pull on the Earth with exactly the same amount of force as the Earth pulls on you! Why does this seem untrue?

𝑚 𝐸𝑎𝑟𝑡ℎ 𝑎 𝐸𝑎𝑟𝑡ℎ = 𝐹 𝑔 = 𝑚 𝑦𝑜𝑢 𝑎 𝑦𝑜𝑢 Newton’s 3rd Law cont’d 𝑚 𝐸𝑎𝑟𝑡ℎ 𝑎 𝐸𝑎𝑟𝑡ℎ = 𝐹 𝑔 = 𝑚 𝑦𝑜𝑢 𝑎 𝑦𝑜𝑢 The mass of the Earth is substantially larger than your mass and thus the resulting acceleration is substantially smaller. Let’s calculate it: (5.972e24 kg)(aEarth)=658 N=(67.07 kg)(9.81 m/s2) Earth’s acceleration is 1.1e-22 m/s2 (that’s tiny!)