# Week 5 (Sep. 9 - 13)

**Reading:**PSE Chap 4, Motion in Two dimensions

**Topics:**This week, we broaden our discussion from one-dimensional to two-dimensional kinematics. We will apply this to understanding

*projectile motion*and

*circular motion.*

**Lab:**none this week. Next week: artillery lab!

**Homework Problems: Due Wednesday noon week 6**

- Soccer problem: A soccer player kicks a ball with an initial speed of 4 m/s at an angle of 30 degrees above the horizontal. How much time is the ball in the air before it lands on the ground? What is the maximum height the ball reaches? What is the ball's range? What is its velocity at the top of its flight (magnitude and direction)? What is its velocity at the moment it strikes the ground? And what is its velocity at the moment it is halfway up to its maximum height? Solution.
- Artillery problem: An ambitious artillery officer wishes to fire a projectile from ground level so that it goes through a small window in a distant tower. The window is 30 meters above ground level. The tower is 8 kilometers from the launch point. The gun is aimed 30 degrees above the horizontal. What must be the muzzle velocity so that the projectile goes into the window? Assume that there is no wind or other drag acting on the projectile while in flight. Solution.

**Quiz:**We will have a quiz on Monday, Sept. 19. I will cover vectors and some projectile motion.