Isaac Newton Arguably the greatest scientific genius ever. Came up with 3 Laws of Motion to explain the observations and analyses of Galileo and Johannes Kepler. Discovered that white light was composed of many colors all mixed together. Invented new mathematical techniques such as calculus and binomial expansion theorem in his study of physics. Published his Laws in 1687 in the book Mathematical Principles of Natural Philosophy.

Newton’s Laws of Motion Newton’s Laws provide the explanation and allow the prediction of an object’s motion. An object’s motion will never change for no reason. The change in an object’s motion is the result of net force.

What is Force? A force is a push or pull on an object. Forces cause an object to accelerate… – To speed up – To slow down – To change direction

Newton’s First Law A body in motion stays in motion at constant velocity and a body at rest stays at rest unless acted upon by a net external force. This law is commonly referred to as the Law of Inertia.

The First Law is Counterintuitive

Net Force Net Force is simply the total force. Since force is a vector, adding forces requires that direction be considered. Only the forces in the direction of motion, or, directly opposite the motion will be added.

What is Zero Net Force? Even though there are forces on the book, they are balanced. Therefore, there is no net force on the book.  F = 0 Physics A book rests on a table. Gravity pulls down on the book. FGFG The table pushes up on the book. FTFT

Implications of Newton’s 1 st Law If there is zero net force on a body, it cannot accelerate, and therefore must move at constant velocity, which means – it cannot turn, – it cannot speed up, – it cannot slow down.

Mass and Inertia Chemists like to define mass as the amount of “stuff” or “matter” a substance has. Physicists define mass as inertia, which is the ability of a body to resist acceleration by a net force.

Newton’s 2 nd Law It takes a lot of pushing or pulling (FORCE) to change how a big mass is moving. Example: – A basketball filled with lead It takes very little pushing or pulling to change how a little mass is moving. Example: A ping pong ball

Newton’s 2 nd Law It is easy to accelerate a small mass It is difficult to accelerate a large mass.

Mass Vs Weight Mass is measured in kilograms (kg) If an object has a lot of mass, it has a lot of inertia. Your weight is the measure of Gravitational Force — or how hard does the Earth pull down on you. Weight is measured in Newtons. One Newton = ¼ of a Pound.