NEWTON’S 2nd LAW

Newton’s 2nd Law and Centripetal Force -Newton’s 1st law stated: An object at rest tends to ____________________________ an object in motion tends to __________________________ as long as the forces are balanced. stay at rest stay in motion change -If the forces are unbalanced, the motion of the object will ___________. -Newton’s 2nd law states (part 1): When an unbalanced force acts on an object, the object will ___________________ in the direction that the unbalanced force points. accelerate -The greater the force on an object, the greater the________________. -The larger the ________ of an object, the larger the force necessary for acceleration. acceleration mass

mass acceleration 2 remember: 1N= 1kg m/s acceleration mass (N) (kg) -Newton’s 2nd law states (part 2): The strength of the force equals the _________ of the object multiplied by the _______________ of the object. Force = __________ x ___________________ F= x mass acceleration 2 remember: 1N= 1kg m/s F acceleration mass (N) (kg) m x a (m/s ) 2 m a Ex. A baseball player hits a 0.1 kilogram baseball to accelerate it at a rate of 4000 meters per second squared. What is the force of the player’s hit? Ex. A stalled car has a mass of 1000 kilograms. It is pushed forward with a force of 2000 newtons. At what rate does the car accelerate? m = 0.1 kg a = 4000 m/s2 0.1 kg x 4000 m/s2 = F = m x a = 400 kg x m/s2 or 400 N a = F m F = 2000N or 2000 kg x m/s2 2000 kg x m/s2 m = 1000 kg 1000 kg = = 2 m/s2

opposite friction pushes pulls circular velocity acceleration Deceleration -To decrease the velocity of an object, the force must be applied in the direction _______________ of the motion. Often this force comes from ___________. opposite friction Centripetal force -This is the force that ___________ or ___________ on an object into a ________________ path. If you recall: -If you change the direction of an object, you change its ________ -If you change the velocity of an object, you change its _________ pushes pulls circular velocity acceleration -Therefore, an object traveling at a constant speed is accelerating when it is not traveling in a straight line. According to Newton’s 2nd law, since the object is accelerating an unbalanced force must be changing the direction of motion.

It is always trying to travel in a straight line B? C C? D? It is always trying to travel in a straight line perpendicular to the string (tangent to the circle), but as long as you are holding the string (applying a force) it must change directions. Which direction will the ball travel after it is released?

gravity 1 accelerate 9.8 2 19.6 9.8 3 29.4 m/s air friction terminal Falling Objects -As objects fall towards the ground they pick up speed due to the force of ______________. -All objects ______________ toward the ground at the same rate. -On earth the acceleration of falling objects is ________m/s2. -Falling objects will continue to accelerate until they reach the ground unless they are acted upon by an opposing force to balance out gravity. A force that commonly opposed the acceleration of falling is __________________. gravity 1 accelerate 9.8 2 19.6 9.8 3 29.4 m/s air friction -When a falling object stops accelerating, it has reached its _______________ __________________. -Ever object falling through air, if it is falling long enough, reaches a terminal velocity terminal velocity

- shape of the object (aerodynamics) -air thickness -Factors that affect terminal velocities: - shape of the object (aerodynamics) -air thickness -How does horizontal motion affect rate of fall? (this arrow will be dropped vetically from the same height at the moment he shoots) -they would hit the ground at the same time!