Presentation on theme: "Chapter 2 Motion in One Dimension 1. Speed 2. Displacement 3. Average and Instantaneous velocity 4. Acceleration 5. Motion Diagrams 6. 1D motion with constant."— Presentation transcript:
Chapter 2 Motion in One Dimension 1. Speed 2. Displacement 3. Average and Instantaneous velocity 4. Acceleration 5. Motion Diagrams 6. 1D motion with constant acceleration 7. Law of falling body
Dynamics What is Dynamics? What is Kinematics?
Objects in Motion How does one describe motion?
Position and Displacement Position Definition Representation Units Displacement Definition Representation Units Difference between displacement and distance
Vector and Scalar Quantities What are vectors? Why do I need them? How do I represent them During problem solving on paper On Diagrams
Speed and Velocity Average Speed Definition Calculation Units Average Velocity Definition Calculation Units Difference between speed and velocity
Finding Average Velocity on graphs
Instantaneous and Uniform Velocity Definition What is it? How do I calculate it from graph? What is uniform velocity?
Example A toy train moves slowly along a straight portion of track according to the graph of position versus time shown. Find a) the average velocity of the total trip, b) the average velocity during the first 4.0s of motion, c) the instantaneous velocity at t=9.0s
Acceleration Definition Representation Units Average acceleration Instantaneous acceleration Uniform acceleration Graphical interpretation
Example A baseball player moves in a straight-line path in order to catch a fly ball hit to the out field. His velocity as a function of time is shown. Find his instantaneous acceleration at points A, B and C.
Relationship Between Acceleration and Velocity
Kinematic Equations Used in situations with uniform acceleration
Example A bus moving at a speed of 40 m/s begins to slow at a rate of 3 m/s each second. Find how far it goes before stopping?
Example An object starts from rest with constant acceleration of 10 m/s 2 along a straight line. Find a) the speed at the end of 5 seconds, b) the average speed at the 5 second interval, c) the distance traveled in 5 seconds.
Graphical Interpretation of the Equation
Galileo Galilee Galileo formulated the laws that govern the motion of objects in free fall Also looked at: Inclined planes Relative motion Thermometers Pendulum
Free Fall What is the Law of falling body? Galileo's hypothesis Representation Value of g for earth Estimated value Approximate value Direction of Why g is not a universal constant?
Free Fall – Cases v o = 0 a = g=-9.8 m/s 2 DroppedThrown down Thrown Up v o ≠ 0 & -ve a = g=-9.8 m/s 2 v o ≠ 0 & +ve a = g=-9.8 m/s 2 everywhere v = 0 Symmetric or non-symmetric
Example A ball is dropped from rest at a height of 50 m above the ground, a) what is the speed just before it hits the ground? b) how long does it take to reach the ground? Ignore air friction
Example Two rocks are thrown vertically up with a velocity of V and 4V. The ratio of the maximum heights reached (h a /h b ) by the rocks is…
Example Jack and Jill walk down the hill to fetch a pail of water. Jack’s walking path is described by the equation y=0.1x+5 and Jill’s walking path is described by the equation y=0.2x+1. If the source of water is 13 meters away, who reached the river first.