What is Physics?•It is the scientific study of matter

and energy and their interaction with one another.

•Energy can take the form of light, electricity, heat, radiation, wavelengths, etc.

•Physics also deals from subatomic particles to entire galaxies.

One Dimension Kinematics

Vocabulary to Know

Motion•Mechanics is the study of the motion of objects.

•It is divided into two KINEMATICS and DYNAMICS.

•Kinematics deals with how objects move.

•Dynamics deals with force and why objects move the way the do.

Motion•Translational motion is moving without rotating (i.e. one dimension). –We will be talking in terms of particles which are considered mathematical points and to have no size.

Frame of References and Displacement

•Any measurement of position, distance, or speed must be made with respect to a reference frame, or frame or reference.

•When talking about motion it is important to specify the speed and the direction of the motion.

•In physics a set of coordinate axes is drawn to represent a frame of reference.

Frame of References and Displacement

•The x-axis is usually used as the line along which the motion takes place.

•The position of an object at any moment is given by its x-coordinate. If the motion is vertical then the y-axis is used to give the position.

Frame of References and Displacement

•There is a distinct difference between distance and displacement.

•Displacement is how far the object is from its starting point.

•Displacement is a quantity that has both magnitude and direction.

•These quantities are called vectors and are represented by arrows in a diagram.

Frame of References and Displacement

•The displacement of an object is usually denoted by the symbol which means the change in. Ex. x is the change in x

Average Velocity•The term “speed” refers to how

far an object travels in a given time interval, regardless of direction.

•The average speed of an object is defined as the total distance traveled along its path divided by the time it takes to travel this distance.

Average Velocity•Speed is simply a positive

number. •Velocity is used to signify

both the magnitude (numerical value) of how fast an object is moving and also the direction in which it is moving.

•Velocity is a vector.

Average Velocity•The average velocity is defined

in terms of displacement, rather than total distance traveled.

Average Velocity•The elapsed time, or time interval , is the time that has passed during the chosen period of observation

Instantaneous Velocity•The instantaneous velocity at

any moment is defined as the average velocity during an infinitesimally short time interval.

Acceleration•An object whose velocity is

changing is said to be accelerating.•Average acceleration is defined

as the change in velocity divided by the time taken to make this change.

Acceleration•Instanteneous acceleration,

a, is defined in analogy to instantaneous velocity, for any specific instant:

Practice