Descriptions of Motion Intro to Mechanics Descriptions of Motion

Statics Kinematics Dynamics MECHANICS Objects at rest/equilibrium Simple descriptions of motion only Dynamics Description of motion and its cause

Note: Establish a reference point before describing motion. When do you say that something has moved? How do you know if there is a change in position? Can an object be described as “had been moving” but has not moved at all? Note: Establish a reference point before describing motion. In problem solving, analyze carefully which is required in your solution, distance or displacement. The mistake starts from there.

Essential: displacement vs. distance Cases when total distance equals total displacement Cases when there is total distance covered but zero total displacement Cases when total displacement is shorter than the total distance

Indications of a change in velocity. Change in its magnitude of speed Change in its direction of movement Change in both magnitude and direction Indications of a change in velocity.

Graphical Representations of motion Kinematics on a Graph Graphical Representations of motion

O d t

O d t

O v t

O a t

A car starts from rest from point O and speeds up at a constant rate until it reaches 20.0 m/s at point A. From point A, a traffic sign indicates a limit speed of 20.0m/s, so the driver decides to maintain his speed until point B. When the car reaches point B, there is a heavy traffic so the driver decides to slow down at a constant rate until it stops at an intersection at C. If the interval between the given points is a constant of 10.0 seconds, determine the total distance covered by the car A car starts from rest from point O and speeds up at a constant rate until it reaches 20.0 m/s at point A. From point A, a traffic sign indicates a limit speed of 20.0m/s, so the driver decides to maintain his speed until point B. When the car reaches point B, there is a heavy traffic so the driver decides to slow down at a constant rate until it stops at an intersection at C. If the interval between the given points is a constant of 10.0 seconds, determine the total distance covered by the car. Motion in a Graph

Kinematics Problem Set 1

An athlete ran a distance of 100. 0 m in 9. 83 s An athlete ran a distance of 100.0 m in 9.83 s. What was his average speed?

A sports car traveling at 30. 0 m/s stops suddenly in 5. 00 seconds A sports car traveling at 30.0 m/s stops suddenly in 5.00 seconds. Find its acceleration.

Practice Exercise 3.4 page 55 Two cyclists race against the clock in a 50.0km cross-country route. Cyclist A travels at a constant speed of 50.0km/h. Cyclist B started 15.0 min after cyclist A but manages to catch up at the finish line. What is the speed of cyclist B assuming that his speed is constant? Practice Exercise 3.4 page 55