advertisement

1. Any push or pull -can cause change in motion: a. friction b. inertia c. burn d. force 2. A force that always works against motion a. friction b. gravity c. inertia d. momentum 3. What is the mass of a female Sumo Wrestler that weighs 750N? Fg=mg a. 7,350kg b. 76.5kg c. 765g d. 73.5g 4. If there is no net force on an object, it will a. not change motion b. change motion c. move NOW IT’S TIME FOR NEWTON’S 2ND LAW Newton’s 1st: Inertia. At rest, stay at rest; in motion, stay in motion. Newton’s 2nd: What happens when a force acts on an object? Acceleration. NEWTON’S SECOND LAW: The acceleration of an object is directly proportional to the force applied to the object, and inversely proportional to the mass. -or – The net force on an object is equal to the mass of the object multiplied by its acceleration. - or – Newton’s Second Law: Force = mass x acceleration Force equals mass times acceleration. F=ma CALCULATE THE FORCE HOW DO WE? HOW? LIKE THIS: My 4 kg cat, Jeter, ran at our new kitten with an acceleration of 3.0 m/s2. He didn’t stop. Poor little kitten! After suffering a mild concussion, we wondered….how much force did Jeter hit him with? Force = mass x acceleration, or… 4 x 3 = 12 12 WHAT? Remember Force has its own special unit… 1kg x 1m/s2 = 1 newton (1N) F = ma Learn it. Live it. Love it. FORCE = MASS(ACCELERATION) 1. How much force is needed to move a mass of 40 kg at 1.5 m/s2? 2. What is the mass of a rock that has an acceleration of 2.3 m/s2 after a force of 2300 Newtons has hit it? 3. How much force must be applied to a toy car that has a mass of .25kg to achieve an acceleration of 2.4m/s2? 4. What is the acceleration of a dog with a mass of 15kg that hits with a force of 300 Netwons? TERMINAL VELOCITY…… Terminal Velocity- object will reach a speed where the force of the drag will become equal the force of gravity