# Week 6 (Sep. 16 - 20)

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

**Topics:**This week, we continue our discussion of 2 - d kinematics, focusing on projectile motion and circular motion.

**Quiz on Monday this week.**

**Artillery Laboratory!**In lab this week, we will be attempting to accurately predict the range of a fired projectile. Your lab grade will depend on the accuracy of your prediction!

**Determine muzzle velocity**: fasten a projectile launcher to your lab bench. Fire the projectile horizontally five times. Use carbon paper on the floor placed over a white sheet of paper to mark the point of impact. Measure the range of the projectile and the height of the center of the barrel. Repeat five times and average your results. Calculate the muzzle velocity of the launcher.**Predict height of vertical launch**: without firing the cannon again, predict, based on your muzzle velocity, the height to which the ball will rise when fired straight upward. Clearly write down your prediction in your lab book. All calculations should be done in your lab book (no where else!). Have the professor come to your laboratory station and fire the projectile straight up and measure the height. Record your result and the percent error. If your error exceeds 8%, Re-evaluate your procedure.**Predict the range of an angled launch**: without firing your cannon again, predict the range when the cannon is fired at a 25 degree angle above the horizontal from your lab bench down onto the floor. Before you fire your gun, write down your prediction and put a box around it. Your grade will depend on the percent error from your prediction! All calculations should be recorded in your lab book. Now place a piece of paper on the floor and draw a horizontal line indicating your predicted distance. Cover the paper with carbon paper, get your professor to watch, and launch the cannon. What is your percent error?