Transcript 24 Slides
IPC Newton’s 1st Law of Motion • Newton’s 1st Law of Motion – Objects in motion will stay in motion and objects at rest will stay at rest…unless a force acts on them. The ball will stay at rest (not move) unless the dog moves it. Newton’s Second Law of Motion • Newton’s Second Law of Motion - "F = ma: the net force on an object is equal to the mass of the object multiplied by its acceleration. You bunt – the ball doesn’t go far. You swing hard (more force), the object accelerates faster. Newtons Third Law of Motion • Newton’s Third Law of Motion - To every force or action, there is always an equal and opposite reaction. • The cannon has a backward kick when it is fired.." Question • What makes an object difficult to stop? Momentum Momentum Momentum Question • A ball of mass 2 kg. is moving with a speed of 4 m/s. What is its momentum? Answer A ball of mass 2 kg. is moving with a speed of 4 m/s. What is its momentum Momentum = (mass)(velocity) = (2 kg)(4 m/s) = 8 kg m/s Mass • More mass means more momentum • Twice the mass means twice the momentum. Law of Conservation of Momentum • For a collision occurring between object 1 and object 2 in an isolated system, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision MV = MV Centripetal Force • Centripetal Force- force directed towards the center of the circle for an object moving in a circular motion. Centripetal Acceleration • Centripetal Acceleration – Acceleration toward the center of a curved or circular path. Friction • Friction - when 2 objects rub together. It generates heat. Example (rub your hands together) Sliding Friction • Sliding Friction- is when two objects are rubbing against each other. Putting a book flat on a desk and moving it around is an example of sliding friction. • Have you ever pushed a box before. Rolling Friction • Rolling friction- is the resistance that occurs when a round object such as a train rolling on a track or a ball rolling on a surface. Air Resistance • Air resistance – Like turbulence…….objects slowing down in the wind. Running into the wind. Weight • Weight – Changes with gravity. It Is different on every planet. Mass • Mass – Always remains the same. Triple Beam balance can measure mass. Law of Gravitation • Law of Gravitation - states that any two objects exert a gravitational force of attraction on each other. The moon’s gravitational force causes tides. Gravity Constant • Gravitational Acceleration (gravity constant) – 9.8 m/s2 (If you get thrown out of a plane, you will accelerate to the eart at 9 m/s2) Projectiles • Projectiles – Objects that are launched and fly through the air (bullets, missiles) Static Fricton • Static friction - Static friction is a force between two objects that are not moving relative to each other.