Physics 218 Lecture 6 Dr. David Toback Physics 218, Lecture VI

Kinematics in Two or Three Dimensions Chapter 3, continued Kinematics in Two or Three Dimensions Problems Physics 218, Lecture VI

Physics 218, Lecture VI

This is the heart and culmination of what we have learned so far Projectile Motion This is the heart and culmination of what we have learned so far You can rest assured there will be a problem like one in lecture today on the exam Physics 218, Lecture VI

Important Definition ;-) Word: Defenestration Definition: The act of throwing someone or something out of a window Physics 218, Lecture VI

Push BEVO out of a window Reveille pushes BEVO directly out of a window a height h above the ground. Two Aggies observe that BEVO hits the ground a distance D from the base of the cliff. Assuming BEVO was moving horizontally at the top (and ignoring air friction), how fast must Reveille have pushed her? h y=0 D Physics 218, Lecture VI

Kick a football A football is kicked at angle Q with respect to the ground with speed V0. Calculate: The maximum height The velocity at the maximum height The time of travel before the football hits the ground How far away it hits the ground What angle maximizes the distance traveled Assume the ball leaves the foot at ground level and ignore air resistance Physics 218, Lecture VI

Winner: Not my job award Physics 218, Lecture VI

More Realistic Punt A football is kicked at angle Q0 with a speed V0. The ball leaves the punters foot h meters above the ground. How far does it travel, in the X direction, before it hits the ground? h Physics 218, Lecture VI

Rescue Plane You are the pilot of a rescue plane and you are flying a plane with a horizontal speed of Vp. Your mission is to drop supplies for some mountain climbers on a ridge a height h below. To do this you have to release the supplies a horizontal distance R in advance of the mountain climbers. What vertical velocity should you give the supplies so that they arrive precisely at the the climbers position? Physics 218, Lecture VI

Next Week Newton’s Laws of Motion Reading Questions: 4.7 and 4.16 New Material: Not on the 1st exam Chapter 4: Read for Next time Newton’s Laws of Motion Reading Questions: 4.7 and 4.16 Due Tuesday at the beginning of class! HW2 due Monday Cover HW3 in recitation, due the following Monday Physics 218, Lecture VI

End of Lecture Notes Physics 218, Lecture VI

Firing up in the air at an angle A ball is fired up in the air with velocity Vo and angle Qo. Ignore air friction. The acceleration due to gravity is g pointing down. What is the final velocity here? Physics 218, Lecture VI

Rescue Plane You are the pilot of a rescue plane. Your mission is to drop supplies to isolated mountain climbers on a rocky ridge a height h below. If your plane is traveling horizontally with a speed of VO: How far in advance of the recipients (horizontal distance) must the goods be dropped? Physics 218, Lecture VI

Rescue Plane cont. Suppose instead, that your plane can’t get to that position. Instead you must release the supplies a horizontal distance D in advance of the mountain climbers. What vertical velocity should you give the supplies so that they arrive precisely at the the climbers position. What is the speed of the supplies as they hit the ground? Physics 218, Lecture VI

Announcements: Exam 1 We will move the date of Exam 1 from Tuesday Feb 11th. Next week you need to do the reading for Chapter 4, Chapter 3-9 and Chapter 5. There will be quizzes on both. Note: You will get recitation on Chapter 3 and turn in your Homework before the exam. Physics 218, Lecture VI

Next Week Finish HW3. Labs & Rec/Web as usual Chapter 4: (NOT ON 1st EXAM) Dynamics Newton’s Laws of Motion Finish HW3. Labs & Rec/Web as usual Exam Thursday: Here during regular time Bring a calculator and ruler Formula sheet will be provided (on the web already) Will cover: Chapter 1 (1-6) Calculus 1 Chapter 2 (1-7) Chapter 3 (1-8, 10) Physics 218, Lecture VI

Example: 3-8 Derive a formula for the horizontal range, R, of a projectile in terms of its initial velocity (v0 & Q) before the projectile travels before returning to its original height Physics 218, Lecture VI