Slide 1

Expedition 3: Fundamental Forces Forces and Laws of Motion Slide 2 Slide 3 Slide 4 Slide 5 http://webpath.follettsoftware.com/resource/viewurl?enc odedUrl=plo2j1Ikxcj5uQozTp- kxdLlZXe3VIeh2JUFcQGT0_Q&version=1&userGUID=41192 717-80A3-450C-8DA0-6CF1AC2834B9&gv=1&gc=- 17299486&appsignature=Destiny&appversion=11.5.3.0+%2 8RC3%29 http://webpath.follettsoftware.com/resource/viewurl?enc odedUrl=plo2j1Ikxcj5uQozTp- kxdLlZXe3VIeh2JUFcQGT0_Q&version=1&userGUID=41192 717-80A3-450C-8DA0-6CF1AC2834B9&gv=1&gc=- 17299486&appsignature=Destiny&appversion=11.5.3.0+%2 8RC3%29 Slide 6 Goals Define force and explain how forces act on matter. Identify the many forces acting on an object to determine the net force on the object. Explore the relationship between force, mass, and acceleration. Apply Newtons Laws of Motion to understand how forces affect an objects motion. Evaluate the impact of forces and motion on society, technological advances, and the exploration of our universe. Slide 7 Expedition 3: Fundamental Forces A force is anything, such as a push or pull, that causes a change in the motion of an object. Slide 8 Expedition 3: Fundamental Forces Force is a vector quantity, so it is described by both its magnitude and the direction in which it acts. Slide 9 Expedition 3: Fundamental Forces Force is measured in the SI unit: newton. Slide 10 Expedition 3: Fundamental Forces Net force is the sum of all forces acting on an object at any given moment. Slide 11 Expedition 3: Fundamental Forces Friction is the force exerted on two touching surfaces, causing a resistance in motion. Slide 12 Free-body diagram A free-body diagram acts as a map of all the forces acting on an object in a given situation Slide 13 Vector arrows are used to show the magnitude, or strength, and direction of all forces in relation to each other. http://www.youtube.com/watch?v=hSQM0ho S6VE http://www.youtube.com/watch?v=hSQM0ho S6VE Slide 14 Balanced and Unbalanced Forces When the net force applied an object is not zero, the forces are described as unbalanced. Slide 15 Inertia is the tendency of an object to resist any change in its motion. Slide 16 Inertia All objects resist changes in motion, so all objects have inertia. Slide 17 Inertia An object that has a small mass, such as a baseball, can be accelerated by a small force. Slide 18 Inertia But accelerating an object whose mass is larger, such as a car, requires a much larger force. Slide 19 Inertia Thus, mass is a measure of inertia. An object whose mass is small has less inertia than an object whose mass is large does. Slide 20 Inertia Thus, mass is a measure of inertia. An object whose mass is small has less inertia than an object whose mass is large does. Slide 21 http://www.youtube.com/watch?v=0acpJty6s ZM&feature=related http://www.youtube.com/watch?v=0acpJty6s ZM&feature=related http://www.youtube.com/watch?v=QbGV6qQ cJrw&feature=related http://www.youtube.com/watch?v=QbGV6qQ cJrw&feature=related Slide 22 http://www.youtube.com/watch?v=0acpJty6s ZM&feature=related http://www.youtube.com/watch?v=0acpJty6s ZM&feature=related http://www.youtube.com/watch?v=QbGV6qQ cJrw&feature=related http://www.youtube.com/watch?v=QbGV6qQ cJrw&feature=related Slide 23 http://www.youtube.com/watch?v=0acpJty6s ZM&feature=related http://www.youtube.com/watch?v=0acpJty6s ZM&feature=related http://www.youtube.com/watch?v=QbGV6qQ cJrw&feature=related http://www.youtube.com/watch?v=QbGV6qQ cJrw&feature=related Slide 24 http://www.youtube.com/watch?v=LEsK9u_2RYk http://www.youtube.com/watch?v=PXoDeyybpx0 http://www.youtube.com/watch?v=R8BfsRHAc7U http://www.youtube.com/watch?v=TI00v8TSSbA http://www.youtube.com/watch?v=7gfWvexu4u4&f eature=related Slide 25 Newtons First Law An object that is moving will continue to move with the same velocity, until an unbalanced force acts on it to stop it, change its speed, or change its direction. Slide 26 Newtons First Law Slide 27 This also means that an object that is motionless will remain motionless unless an unbalanced force acts on it. Slide 28 Newtons First Law The Coefficient of friction is the degree of resistance of a surface. Slide 29 The larger the coefficient of friction is between any two objects, the more force is required to move the objects and keep them in motion. Slide 30 Static friction acts on objects that are not moving. Kinetic friction acts on objects that are in motion. Slide 31 Kinetic (moving) friction can be further broken down into three basic types: sliding, rolling, and fluid. Slide 32 More force is usually needed to overcome static friction than kinetic friction. Slide 33 Slide 34 Newtons Second Law of Motion When a force is applied to an object, the object will accelerate. Slide 35 Newtons Second Law Newtons second law: The unbalanced force acting on an object equals the objects mass times its acceleration. Slide 36 Newtons Second Law of Motion The relationship between force and acceleration is described in the equation: force equals an objects mass multiplied by its acceleration. F = m x a Slide 37 Newtons Cannon http://waowen.screaming.net/revision/force& motion/ncananim.htm http://waowen.screaming.net/revision/force& motion/ncananim.htm Slide 38 F = m x a Force is measured in newtons. One newton is the force that gives a mass of one kilogram an acceleration of one meter per second squared: 1 N = 1 kg 1 m/s 2 The pound (lb) is sometimes used as a unit of force. One newton is equal to 0.225 lb. Conversely, 1 lb equals 4.45 N. Slide 39 Slide 40 Mike's car, which weighs 1,000 kg, is out of gas. Mike is trying to push the car to a gas station, and he makes the car go 0.05 m/s/s. Using Newton's Second Law, you can compute how much force Mike is applying to the car Slide 41 Answer = 50 newtons Slide 42 Slide 43 The Force of Gravity All objects with mass are attracted to each other by a type of force called gravitational- force. Slide 44 The Force of Gravity The magnitude of this force depends on the mass of the two objects and the distance between them. Slide 45 Law of Universal Gravitation When the masses are very large, however, the gravitational force will be strong enough to hold the planets, stars, and galaxies together. Slide 46 The force of gravity causes objects to accelerate as they fall. On Earth, the force of gravity causes free- falling objects to accelerate at a constant rate of about 9.8 m/s 2. This is known as gravitational acceleration(g). Slide 47 http://www.absorblearning.com/media/attachment.action?quick=54&att=360 http://www.absorblearning.com/media/attachment.action?quick=54&att=360 Terminal velocity When the only force acting on a falling object is gravity, that object is said to be in freefall. Slide 48 http://www.youtube.com/watch?v=5C5_dOEy Afk http://www.youtube.com/watch?v=5C5_dOEy Afk http://www.youtube.com/watch?v=5N9t5qOS zCU http://www.youtube.com/watch?v=5N9t5qOS zCU Slide 49 Weight and Mass Mass and weight are often confused with each other. Mass measures the amount of matter in an object. Weight measures the gravitational force exerted on an object Slide 50 Weight is measured in newtons. For example, a 66 kg astronaut weighs 66 kg 9.8 m/s2 = 650 N (about 150 lb) on Earth. On the moons surface, where g is only 1.6 m/s2, the astronaut would weigh 66 kg 1.6 m/s2, which equals only 110 N (about 24 lb). Slide 51 Slide 52 Slide 53 Newtons Third Law Newtons third Law of Motion states that for every action force, there is an equal and opposite reaction force. Slide 54 Slide 55 Newtons Third Law When one object exerts a force on a second object, the second object exerts a force equal in size and opposite in direction on the first object. Slide 56 Newtons Third Law For example when you kick a soccer ball the force exerted on the ball by your foot is called the action force, and the force exerted on your foot by the ball is called the reaction force. Slide 57 Forces always occur in pairs. Action and reaction forces are applied to different objects. These forces are equal and opposite. Slide 58 Forces always occur in pairs. Action and reaction force pairs are present even when there is no motion.(EX sitting in a chair) Slide 59 Forces in a force pair do not act on the same object.. Newtons third law states that forces happen in pairs. Slide 60 Newtons Third Law Slide 61 Slide 62 Slide 63 Newtons Third Law http://www.youtube.com/watch?v=jO6B0yx3 FHE http://www.youtube.com/watch?v=jO6B0yx3 FHE Slide 64 Terminal Velocity http://www.absorblearning.com/media/attac hment.action?quick=54&att=360 http://www.absorblearning.com/media/attac hment.action?quick=54&att=360 Slide 65 Review http://www.youtube.com/watch?v=mn34mnn DnKU http://www.youtube.com/watch?v=mn34mnn DnKU