1. Aristotle 384 – 322 BC

2. 1564 - 1642

3. 1643 - 1727 ISAAC NEWTON

4. An object continues in a state of rest or in a state of motion at a constant speed along a straight line, unless compelled to change that state by a net force. The net force is the vector sum of all of the forces acting on an object. Newton ’ s First Law

5. Inertia is the natural tendency of an object to remain at rest in motion at a constant speed along a straight line. The mass of an object is a quantitative measure of inertia. SI Unit of Mass: kilogram (kg)

6. An object is resting on a flat surface An object is being pulled on a flat surface, but is not moving

7. An object is being pulled at a constant speed on a flat surface An object is being pulled with a force that is making an angle with the horizontal. The object is not moving

8. An object is being pulled with a force that is making an angle with the horizontal. The object is moving with a constant velocity An object is being pulled with a force that is making an angle with the horizontal. The object is not moving

9. NEWTON’S II LAW When a net external force acts on an object with mass m, the acceleration that results is directly proportional to the net force and has a magnitude that is inversely proportional to the mass. The direction of the acceleration is the same as the direction of the force.

10. [NEWTON]= [N] [N] = [kg ·m/s 2 ] A net force of 1N exerted on an object with a mass of 1 kg will result in the object moving with an acceleration of 1 m/s 2

12. EXAMPLE Space-shuttle astronauts experience accelerations of about 35 m/s 2 during takeoff. What force does a 75 kg astronaut experience during an acceleration of this magnitude?

13. EXAMPLE A block with a mass of 5 kg is being pulled across a tabletop by a force of 10 N applied by a string tied to the front end of the block. The table exerts a 2-N frictional force on the block. What is the acceleration of the block? 2N 10 N

14. EXAMPLE A 7.5 kg bowling ball initially at rest is dropped from the top of an 11m building. It hits the ground 1.5s later. Find the net external force on the falling ball.

15. REDRAW FOR ACCELERATED MOTION An object is being pulled on a flat surface, and is moving with acceleration An object is being pulled with a force that is making an angle with the horizontal. The object is moving with acceleration