Chapter Summary
PREVIEW
In this chapter you will learn how to describe the motion of an object in one dimension, that is, straight line motion. You will be introduced to the concepts of displacement, speed, velocity, and acceleration. Equations for straight line motion with constant acceleration are developed, with applications including freely falling bodies.
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Important Terms
Mechanics
The branch of physics that deals with the motion of objects and the forces that change it.
Kinematics
A branch of mechanics which describes the motion of an object without explicit reference to the forces that act on the object.
Displacement
A vector representing the change in the position of an object, drawn from the initial to the final position. The most common units for displacement are meters (m), centimeters (cm), or feet (ft).
Average Speed
The distance (a scalar quantity) an object moves in a given amount of time divided by the time. Units are (m/s), (cm/s), or (ft/s).
Average Velocity
The displacement (a vector quantity) of an object divided by the elapsed time. Units are the same as average speed.
Average Acceleration
The change in the velocity (a vector quantity) of an object divided by the elapsed time. Units are (m/s2), (cm/s2), or (ft/s2).
Instantaneous Velocity
The rate of change of displacement. Units are (m/s), (cm/s), or (ft/s).
Instantaneous Speed
The magnitude of the instantaneous velocity vector. Units are the same as instantaneous velocity.
Instantaneous Acceleration
The rate of change of velocity. Units are (m/s2), (cm/s2), or (ft/s2).
Free Fall
An idealized motion, in which air resistance is neglected and the acceleration is nearly constant. This acceleration is due to gravity and taken to be 9.80 m/s2
or 32.2 ft/s2
at the surface of the earth.
Kinematic Equations for One Dimensional Motion (Constant Acceleration)
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