* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Inertia - bYTEBoss
Survey
Document related concepts
Modified Newtonian dynamics wikipedia , lookup
Coriolis force wikipedia , lookup
Classical mechanics wikipedia , lookup
Equations of motion wikipedia , lookup
Nuclear force wikipedia , lookup
Newton's theorem of revolving orbits wikipedia , lookup
Fundamental interaction wikipedia , lookup
Seismometer wikipedia , lookup
Fictitious force wikipedia , lookup
Rigid body dynamics wikipedia , lookup
Centrifugal force wikipedia , lookup
Classical central-force problem wikipedia , lookup
Centripetal force wikipedia , lookup
Transcript
Dynamics 1 Dynamics • Study of the interactions between force and motion 2 Force • A force is something that is CAPABLE of causing an object (mass) to change its velocity 3 Force • A force is something that is CAPABLE of causing an object (mass) to change its velocity Change in speed 4 Force • A force is something that is CAPABLE of causing an object (mass) to change its velocity Change in speed or Change in direction 5 Force • A force is something that is CAPABLE of causing an object (mass) to change its velocity Change in speed or Change in direction or Both change direction and speed 6 Force • To be CAPABLE does not mean it must happen – A force will not always cause a change in velocity 7 Force • To be CAPABLE does not mean it must happen – A force will not always cause a change in velocity • The force must be unbalanced to cause a change in velocity 8 Force • To be CAPABLE does not mean it must happen – A force will not always cause a change in velocity • The force must be unbalanced to cause a change in velocity • Net Force ≠ zero 9 Force • To be CAPABLE does not mean it must happen – A force will not always cause a change in velocity • The force must be unbalanced to cause a change in velocity • • Net Force ≠ zero Net Force = sum of all forces acting on an object 10 Force • To be CAPABLE does not mean it must happen – A force will not always cause a change in velocity • The force must be unbalanced to cause a change in velocity • • • Net Force ≠ zero Net Force = sum of all forces acting on an object FNet = F1 + F2 + F3 +….. Fn 11 Force • To be CAPABLE does not mean it must happen – A force will not always cause a change in velocity • The force must be unbalanced to cause a change in velocity • • • • Net Force ≠ zero Net Force = sum of all forces acting on an object FNet = F1 + F2 + F3 +….. Fn FNet = ∑ F1-n 12 Force • If the Net Force ≠ zero – The object being acted upon must accelerate 13 4.1 The Concepts of Force and Net Force This figure illustrates what happens in the presence of zero and nonzero net force. 14 Force • When the object exposed to the unbalanced force begins to accelerate; The forces are effectively balanced 15 Force 16 Force • When the object exposed to the unbalanced force begins to accelerate; The forces are effectively balanced 17 Force • When the object exposed to the unbalanced force begins to accelerate; The forces are effectively balanced The excessive force causes an acceleration in the direction of the unbalanced force 18 Force • When the object exposed to the unbalanced force begins to accelerate; The forces are effectively balanced The excessive force causes an acceleration in the direction of the unbalanced force The acceleration is directly proportional to magnitude of the unbalanced force 19 Types of Forces • Two broad categories of forces 20 Types of Forces • Two broad categories of forces • Contact forces 21 Types of Forces • Two broad categories of forces • Contact forces • Field forces 22 Types of Forces • Two broad categories of forces • Contact forces • Field forces » forces that act at a distance 23 Contact Force • The surfaces of two separate objects are in contact • Push • Pull • friction • Tension from a rope, string, etc. 24 Field Force • Force that acts without direct surface contact • Force acts at a distance »gravity, »electric force »magnetic force »strong nuclear force »weak nuclear force 25 Inertia • Inertia is the natural tendency of an object to maintain its current state of motion • An object at rest will tend to remain at rest • An object in motion will tend to maintain its current state of motion » Same speed » Same direction 26 Inertia • Galileo developed the concept of Inertia 27 Inertia • Galileo developed the concept of Inertia • Inertia is a property of matter that causes it to resist changes in its velocity 28 Inertia • Galileo developed the concept of Inertia • Inertia is a property of matter that causes it to resist changes in its velocity • Inertia is directly proportional to mass 29 Inertia • Galileo developed the concept of Inertia • Inertia is a property of matter that causes it to resist changes in its velocity • Inertia is directly proportional to mass • As mass increases inertia increases 30 Inertia • Galileo developed the concept of Inertia • Inertia is a property of matter that causes it to resist changes in its velocity • Inertia is directly proportional to mass • As mass increases inertia increases • As mass decreases inertia decreases 31 Inertia • Galileo developed the concept of Inertia • Inertia is a property of matter that causes it to resist changes in its velocity • Mass is a quantitative measure of inertia • As mass increases inertia increases » Double the mass---------double the inertia » Triple the mass -----------triple the inertia » Half the mass ------------- half the inertia 32 Inertia • Galileo performed experiments by carefully observing and measuring objects that rolled down and then up inclines of various angles 33 • According to Aristotle, the natural state of objects was to be at rest, and if you got them moving, eventually they would come to rest again. • Galileo did experiments rolling balls down and up inclined planes, and realized that, in the absence of some kind of force, an object would keep moving forever once it got started 34 Inertia • It is difficult to observe objects free falling under the influence of gravity. The objects move fast and accelerate to quickly 35 Inertia • It is difficult to observe objects free falling under the influence of gravity. The objects move fast and accelerate to quickly • By using inclines and simple trigonometry Galileo was able analyze mass and resulting acceleration as influenced by the constant force of gravity. 36 Newton’s 3 Laws of Motion • 1st Law of Motion – Often called the Law of Inertia • Heavily influenced by Galileo’s concept of inertia In the absence of an unbalanced applied force (Fnet = 0), a body at rest remains at rest, and a body already in motion remains in motion with a constant velocity (constant speed and direction). 37 Newton’s 3 Laws of Motion • 2nd Law of Motion – Experiments show that the acceleration of an object is directly proportional to the force exerted on it and inversely proportional to its mass. 38 Newton’s 3 Laws of Motion • 2nd Law of Motion The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The direction of the acceleration is in the direction of the applied net force. 39 Newton’s 3 Laws of Motion 3rd Law of Motion For every force (action), there is an equal and opposite force (reaction). 1 1 40 2nd Law of Motion •F = ma 41 2nd Law of Motion • SI Units of Force F = ma 1 Newton = 1 kg(1m/s2) 42 2nd Law of Motion • SI Units of Force F = ma 43 2nd Law of Motion • SI Units of Force F = ma 1 Newton = 1 kg(1m/s2) 2 1N = kg∙m/s 44 2nd Law of Motion • Weight • A Force that is always directed towards the center of the earth • F = ma • Weight = m(g) • Weight is understood to be directed downward. So it is never labeled negative 45 Weight 46 Weight • What is the weight of a 12 kg mass on earth? 47 Weight • What is the weight of a 12 kg mass on earth? Weight = m(g) Weight = 12 kg( 9.8m/s2) Weight = 117.6 N = 120 N 48 Weight • Weight is perpendicular to the center of the mass generating the gravitational field 120N 49 Weight on an Incline What is direction of weight? 50 Normal Force Normal Force is the force of a surface against an object resting on the surface The normal force( FN ) is always perpendicular to the surface 51 Normal Force Normal Force is the force of a surface against an object resting on the surface The normal force( FN ) is always perpendicular to the surface The normal force will support the object on the surface 52 Normal Force Normal Force is the force of a surface against an object resting on the surface The normal force equals the weight of the object on a level surface 53 Weight on an Incline What is direction of weight? 54 Normal Force on an Incline Normal force is perpendicular to the surface 55 Normal Force on an Incline Normal force is usually less than the weight on an incline F N < FW 56 57