Transcript ch2quizrev
Projectile motion The curved path that an object follows when thrown, launched, or otherwise projected near the surface of the Earth. Centripetal force: An unbalanced force meaning “towards the center” that causes objects to move in a circular path. Inertia The tendency of an object to resist a change in motion until acted on by an unbalanced force . Action/reaction pairs All forces act in pairs The action of one object causes the equal and opposite reaction of the other Momentum “Mass in motion”; the product of the mass and velocity of an object. Law of Conservation of Momentum Any time that objects collide, the total momentum will stay the same Newton’s First Law: An object at rest will stay at rest and an object in motion will stay in motion until acted on by an unbalanced force. Newton’s Second Law: Acceleration depends on force and mass How is it expressed mathematically? A = F/m Example : Pushing a shopping cart full of groceries requires more force than an empty cart if you want to keep the acceleration the same Newton’s Third Law: For every action there is an equal and opposite reaction example: rocket What gives an object in projectile motion it’s vertical motion? Gravity If you are shooting an arrow trying to hit the bulls eye of a target, explain where you must aim the arrow and why. You must aim higher than the bulls eye because you need to account for gravity impacting the vertical motion and pulling the arrow down. Provide an example of an object in projectile motion. Frog jumping Ball being thrown Bullet being shot Explain the motion of an unsecured object in a car traveling at 100 miles per hour and the brakes are suddenly slammed on – use scientific terms we have learned! The object will continue to move forward because of inertia. It will keep moving until acted on by an unbalanced force(like hitting the windshield) Name two factors that influence an object’s inertia. Mass and friction Calculate the acceleration of a 40 kg object that is pushed with a 2N force. a = F/m a = 2 kg X m/s2 40 kg a = .05 m/s2 Calculate the acceleration of a 80 kg object that is pushed with a 2N force. a = F/m a = 2 kg X m/s2 80 kg a = .025 m/s2 What happens to an object’s acceleration if the mass increases and the force remains the same? Acceleration will increase What happens to an object’s acceleration as the force increases, but the mass remains the same? Acceleration will increase Provide an example of an action-reaction pair. Baseball bat hitting ball Bowling ball hitting pins Rocket blasting off Balloon car moving What can happen to momentum when 2 objects collide? All or some of the momentum will be transferred to the other object Which of Newton’s Laws does each of the following examples apply to? 1 A bicyclist flying over the handle bars when the brakes are applied suddenly. 3 A rocket blasting off 2 A woman pushing a baby carriage with a 4 kg baby in it. Which will require more force to accelerate an object at the same rate, a bowling ball or a golf ball? Explain why. A bowling ball will require more force because it has more mass. If a bus and a bike are traveling with the same velocity do they have the same momentum? Explain your answer. A bus will have more momentum because it has a larger mass than the bike does. Use Newton’s law of inertia, centripetal force and gravity to explain why planets orbit the Sun. The inertia that planets have (left over from the big bang) that causes it to “want” t travel away is balanced by the gravitiation force of the Sun which causes a centripetal force and causes the planets to orbit the Sun.