OVERVIEW Kinematics Motion Ch 2 3 Mechanics Dynamics

OVERVIEW Kinematics (Motion) Ch. 2 & 3 Mechanics Dynamics (Forces) Ch. 4

UNIT 1: KINEMATICS IN ONE DIMENSION AKA Linear Motion

PART ONE: DISPLACEMENT, VELOCITY, AND ACCELERATION Book Sections 2. 1 -2. 3

WORDS TO KNOW • Rate: quantity divided by time • Ex: meters per second (m/s) or Liters per minute (L/min) • Relative: in relation to or with respect to • Constant: staying the same

DISTANCE VS. DISPLACEMENT • Distance • the extent of space between points OR • how much ground an object has covered during motion • scalar • Ft, m, cm, in, miles •

DISPLACEMENT •

PRACTICE PROBLEM 1 • A honeybee leaves the hive and travels a total distance of 2 km before returning to the hive. What is the magnitude of the displacement vector of the bee? • Displacement = 0 km. Since the bee returns to the hive, he has no overall change in position.

PRACTICE PROBLEM 2 A cat walks back and forth on a ledge. It walks 13 m east, turns around and walks 15 m west, and turns around again and walks 10 m east. • What is the total distance traveled by the cat? • Distance = 13 + 15 + 10 = 38 m. • What are the magnitude and direction of the displacement vector? • Displacement = 13 – 15 + 10 = 8 m east.

PRACTICE PROBLEM 3 Determine the magnitude and direction (positive or negative) of the displacement vectors. • Initial position = -4. 0 cm, final position = +5. 0 cm • Displacement = final – initial = 5. 0 – (-4. 0) = +9. 0 cm • Initial position = 8. 0 cm, final position = -2. 0 cm • Displacement = final – initial = -2. 0 – 8. 0 = -10. 0 cm

SPEED •

VELOCITY •

VELOCIT Y • Instantaneous Speed/Velocity - measured at a specific point instead of over the total duration • Like a cop with a radar gun • When we just refer to “speed” or “velocity” we usually mean instantaneous. • Constant Velocity - the object’s motion is maintained in a straight line with out a decrease or increase

PRACTICE PROBLEM 4 •

PRACTICE PROBLEM 5 •

PRACTICE PROBLEM 6 •

PRACTICE PROBLEM 7 •

PRACTICE PROBLEM 8 •

ACCELERATION •

ACCELERATIO N • Three ways to cause an acceleration • Speed up (a > 0) • Slow down (deceleration a < 0) • Change direction • If velocity is constant AND not changing direction, then a = 0. • Instantaneous Acceleration – measured at a particular instant in time.

PRACTICE PROBLEM 9 •

PRACTICE PROBLEM 10 •

PRACTICE PROBLEM 11 •