Presentation on theme: "Reading Assignment: (3.1) What is this vector indicating? A.A velocity with a 1.5 cm component B.A displacement with a 1.5 cm component C.A displacement."— Presentation transcript:
Reading Assignment: (3.1) What is this vector indicating? A.A velocity with a 1.5 cm component B.A displacement with a 1.5 cm component C.A displacement vector with the components (3.0 cm, 4.5 cm) D.A position vector to a place at (3.0 cm. 4.5 cm)
In a dance, you are standing in a spot, and your partner is located 5 steps to the right of you. He takes 5 steps back, 10 steps to his left. Which displacement does he need to undergo to end up beside you? Draw the picture for the following problem, label, and write an appropriate vector equation: Short exercise
You are observing deer. First, you spot the buck 200m at NNE. A few seconds later, he surfaces again north of you. From the time that has passed you determine that the buck can not have further than 80 m away from the first position. What is the buck’s new position vector? Draw the picture for the following problem, label, and write an appropriate vector equation: Short exercise
Refinement for average velocity observer defines reference point Position vector Time t 1 Position vector Time t 2 Displacement vector Average velocity: change in position over time Position vectors: bound to a reference point
You watch a ground hog poke his head out of a hole 20m due North of your position. About 15 s later, he appears at a distance of 45 m West of you. a)Determine its displacement. b)Determine its average velocity.
Instantaneous velocity Direction of average velocity? Strategy: bring the two points closer together.
Velocity vector? Speed? What are those components?
Average acceleration Change in velocity? Rate of change in velocity? Average acceleration is the average rate of change in instantaneous velocity.
Instantaneous acceleration Change in velocity?
Reading Assignment: (3.2) Which of the particles below has zero acceleration? A.A baseball is flying beyond the playing field for a home run. B.A child in a Ferris Wheel being spun around at constant speed. C.A glider is sliding off an inclined air track. D.A car is slowing down on an icy straight road.
A ship’s echo on a radar screen is moving according to in which all lengths are in km and times in hours. a)Find the position at time zero, after 30 min and after 1 hour. b)Find the velocity as a function of time; then calculate it at time zero, 30 min and 1h. c)Find the acceleration as a function of time; then calculate the acceleration at zero. 30 min and 1 h. d)Draw positions into an x-y coordinate system, and indicate the respective velocity and acceleration vectors.
Example A toy train is traveling around a circular track. Its position changes with time as a)Find the position of the train after 5 s. b)Find the velocity of the train after 5 s. x y