2. MOTION & FORCES VOCABULARY

3. MOTION The process of continual change in the physical position of an object (distance) relative to reference point ; With direction  N-S-E-W, up-down

4. SPEED The ratio of the distance traveled by an object (regardless of its direction) to the time required to travel that distance. Speed = distance / time

5. VELOCITY The speed and direction of motion of a moving body; the rate of change of its position in a particular direction with time. DIRECTION MATTERS !

6. ACCELERATION The time rate of change of the velocity of a moving body with respect to magnitude or direction; the derivative of velocity with respect to time. A = V final – V initial / time

7. FORCE A push or a pull exerted on an object in order to change the motion of the objects; force has size and direction. F = m x a

8. NEWTON (N) The SI derived unit used to measure force. One newton is equal to the force needed to accelerate a mass of one kilogram one meter per second per second. One newton is equal to the force needed to accelerate a mass of one kilogram one meter per second per second.

9. FRICTION A force on objects or substances in contact with each other that resists motion of the objects or substances relative to each other; a resistance encountered when one body moves relative to another body with which it is in contact.

10. GRAVITY The force of attraction by which terrestrial bodies tend to fall toward the center of the Earth; the fundamental force of attraction that all objects with mass have for each other.

11. WEIGHT The force that gravitation exerts upon a body, equal to the mass of the body times the local acceleration of gravity Depends on its mass & the strength of the gravitational pull. The SI unit of weight is the newton.

12. MASS A measure of the amount of matter contained in or constituting a physical body. The mass of an object is related to the force required to accelerate it and hence is related to its inertia, and is essential to Newton's laws of motion. In most scientific applications, the SI unit of kilogram is used.

13. FREE FALL Free descent of a body in which the gravitational force is the only force acting on it. A satellite in orbit is in free fall, as is a skydiver (if we neglect the effects of air resistance).

14. INERTIA The resistance of a body to changes in its momentum. Because of inertia, a body at rest remains at rest, and a body in motion continues moving in a straight line and at a constant speed, unless it is acted upon by an external force is applied to it.

15. MOMENTUM A vector quantity that expresses the relation of the velocity of a body, wave, field, or other physical system, to its energy. The direction of the momentum of a single object indicates the direction of its motion. Momentum is a conserved quantity (it remains constant unless acted upon by an outside force.

16. PROJECTILE MOTION The curved path that an object follows when thrown, launched, or otherwise projected near the surface of Earth.

17. AIR RESISTANCE The opposition of the atmosphere to forward movement; also called aerodynamic drag.