Forces Acting On Objects Moving and Stopping Mechanisms Newtons f= ma 9.8meters/Sec 2 w= mg Kinetic Friction

Nature of Mass Mass is a Fundamental Property of Matter 1,000 Cubic Centimeters of Water 1 Kilogram Mass =

View of Africa and Saudi Arabia from Apollo 17. Probably the most requested picture of the Earth, this picture was taken by the Apollo 17 astronauts as they left earth orbit en route to the Moon. Taken on Dec. 7, 1972, it was the first time that the trajectory of an Apollo mission enabled a view of the south pole. Gravity is force that causes all objects (matter) to accelerate towards each other At a constant rate and with a force proportional to their Mass

View of Africa and Saudi Arabia from Apollo 17. Probably the most requested picture of the Earth, this picture was taken by the Apollo 17 astronauts as they left earth orbit en route to the Moon. Taken on Dec. 7, 1972, it was the first time that the trajectory of an Apollo mission enabled a view of the south pole. Objects on the Earth’s Surface accelerate down at a rate = 9.8 Meters per Second 2

All Objects (Matter) Exert a Gravitational Force On One Another Proportional to Their Mass Gravity is the Weakest of the 4 Natural Forces

Weight Gravity’s Effect on Mass Weight is a Force measured in Newtons Magnitude: Relative to the Mass Direction: Center of the Earth Weight = Mass x Acceleration of Gravity 9.8 (Newtons) =1 (kg) 9.8 (Meters/Sec 2 ) W (Newtons) = m (kg) g (Meters/Sec 2 )

(W) Weight = 5 kg or 49 Newtons fsfs F W= mg M1M1 Spring Scale Weight is a Force Caused by Gravity Acting on the Mass of an Object 49 Newtons = 5kg x 9.8m/s/s Weight = Mass x Gravity N

Stamp Issued by Germany on Jan. 14, 1993, on his 350th birthday Image Courtesy of University of St.Andrews, Turnbull Server Newton Provided Insights Into the Nature of Forces

Let’s Look at a Pair of Balanced Forces Acting on a Robot Resting on the Floor Because the Floor Pushes Up with the SAME Force The Force of Gravity Acts to Accelerate This Chassis Towards the Earth’s Center The Chassis is undergoing an Acceleration, but it is Not Moving

Newton’s 1 st Law An object with no net force acting on it moves with constant velocity. Force: 20 Newtons Same Force in Opposite Directions There is no NET force on the system and the machines remain stationary Velocity = 0

Newton’s 2 nd Law The acceleration of a body is directly proportional to the net force acting on it and inversely proportional to its mass. Robot Mass = 5 Kilograms Acceleration = 4 meters/sec 2 Tractive Force = 20 Newtons Force = Mass x Acceleration 20N = 5kg x 4m/s 2

Build Newton’s Cart using the GEARS-IDS components and experiment with Newton’s second law f force = m mass a acceleration Newton’s 2 cd Law Pulley Newton’s Cart Mass Force Experiment with masses and forces, and their affect on acceleration

Using Newton’s Cart 1.) Set the System Up on a High Flat Table Pulley Cart 2.) Connect a Masons String from the Cart Through the Pulley 3.) Attach a Weight (Force) to the end of the Pulley Side of the Line 4.) Place a Known Mass on the Cart Note: Separate the Cart and Pulley by 2x Table Height 5.) Allow the Weight to Drop and Time the Speed of the Cart Over a Known Distance

Calculate the Acceleration of the Cart Where: C a = Acceleration of the Cart in meters/sec/sec D = Distance Covered in meters T = Time in seconds

Newton’s Third Law When one object exerts a force on a second object, the second exerts a force on the first that is equal in magnitude but opposite in direction. The rotating wheels push against the floor and propel the robot forward and the floor backwards Floor Momentum = mass x velocity Floor Momentum = 15 kg x 5 mps = 75 Robot Momentum = mass x velocity Robot Momentum = 5 kg x 15 mps = 75 Floor Board Rests on Frictionless Bearing

The End