1. Motion, Forces and Newton's Laws

2. Newton’s First Law • An object in motion will stay in motion at a constant velocity and objects at rest will stay at rest unless acted upon by an outside force. This is also known as the law of inertia.   Inertia is a tendency of an object to resist change in its state of motion.  More massive objects have more inertia.  

3. Newton’s Second Law • Acceleration is proportional to the Force applied to a mass (a=F/m) • [The force applied to an object depends on how big it is (mass) and how much change in speed it has (acceleration).] {Force=mass x acceleration (F=ma).}

4. Newton’s Third Law • For every action (force), there is a reaction (force) equal in strength and opposite in direction. • This is known as the action/reaction law. • Objects exert a force even when they are not moving. All objects have inertia and will resist motion. When you push on something, that resisting force pushes back with the same force

5. Speed and Velocity • Speed is how far an object moves in a certain amount of time; how fast it is moving (75 km / hour). • Speed = distance / time • S = d / t • Velocity is measure of how fast something is moving in a certain direction. (50 meters/second NW) • Velocity = distance & direction / time • V = d / t

6. Distance and Displacement • Distance – measure of how far an object traveled • Displacement – measure distance between the starting and ending points E S

7. Balanced and Unbalanced Forces • A balanced force is a pair of forces that produces no acceleration. • You push on a wall with a force and the wall pushes back you on with its own force. Neither you, nor the wall moves. • if in motion, will be at constant velocity • An unbalanced force is a pair of forces that produces acceleration • You push a box across the floor to the other side of the room.

8. Acceleration • changingspeedand/ordirection • speeding up (positive acceleration) • slowing down (negative acceleration). • acceleration can be calculated in two ways: • acceleration = (final speed – initial speed) / time a = ( sf – si ) / t • acceleration = Force / mass ( a = F / m )

9. Friction and Momentum • Friction is a force that resists motion • It slows things down • Friction on an object moving through air is called Air Resistance • Momentum is the measure of how an object resists changing its movement (a measure of inertia) • Momentum = mass x velocity ( p = mv )

10. Gravity • Gravity causes falling objects on Earth to accelerate at a rate of 9.8 m/s2 (also known as 1 G). • This means that when an object is in freefall, every second it increases its speed by 9.8 m/s. • How fast would an object be falling after 5 seconds? = 5 G; or 49 m/s • Weight is a measure of the gravitational force acting on an object’s mass. • Video – Apollo moon drop