The Study of Forces that cause Motion Dynamics The Study of Forces that cause Motion

Dynamics Dynamics is the study of why things move. Dynamics focuses on the forces that cause objects to change their state of motion (e.g. Speed up/Slow down/change direction – accelerate)

Forces Forces are things that cause a push or a pull action. Forces cause things to change their state of motion. Forces have size (magnitude) and direction. This makes them a vector quantity. Measured in units of Newtons (N) named after Sir Isaac Newton) – the “father” of classical physics.

FORCES There are four fundamental forces of nature... Gravity (very weak) Attractive only Weak Nuclear (1025 X stronger than gravity) Inside the nucleus (attractive & repulsive) Electromagnetic (1036 X stronger than gravity) Electric charges, magnetism, light (attractive & repulsive) Strong Nuclear (1038 X stronger than gravity) Holds the nucleus of an atom together (attractive & repulsive)

Newton’s laws of motion The laws of motion were first developed by Sir Isaac Newton in the 1600s understand how forces influence motion. Mathematician & Physicist Years:1643-1727

Newton’s Accomplishments In his twenties he worked on a series of papers called the Principia which outlined the laws of motion and gravity. Newton also made one of the first reflecting telescopes and developed his own theory of colour and light. Newton also developed an entire branch of mathematics called Calculus. This was necessary to do the science he was developing.

His work...

Famous quote “If I have seen farther than other men, it is because I stood on the shoulders of giants.”

Newton’s laws of motion Newton wrote 3 fundamental laws of motion – these laws deal with: Inertia force/mass/acceleration action-reaction forces

Demonstrations Your teacher will now do a number of demonstrations to help you understand and grasp the meaning of NEWTON’s FIRST LAW – THE LAW OF INTERTIA!

http://www.youtube.com/watch?v=ohC_vunbUAA Newton’s first law Skateboard Basket Transfer http://www.youtube.com/watch?v=ohC_vunbUAA

http://www.youtube.com/watch?v=8zsE3mpZ6Hw NEWTON’S FIRST LAW Car Seatbelts and Head-rests http://www.youtube.com/watch?v=8zsE3mpZ6Hw

http://www.youtube.com/watch?v=mk7VWcuVOf0 NEWTON’S FIRST LAW “They’ve gone to plaid!” http://www.youtube.com/watch?v=mk7VWcuVOf0

Law of intertia Newton’s First Law Mass is a measure of inertia Inertia is a measure of an object’s resistance to change in motion. An object at rest tends to stay at rest An object in motion tends to stay in motion An object’s motion is only changed if an external force acts on it Mass is a measure of inertia Inertia can be better formalized as a resistance to change in motion More mass  more inertia (more resistance to change in motion)