Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.

Compute the muzzle velocity of a tilted cannon

Your job in this exercise is to watch very carefully as a ball is shot out of a gun, flies through the air, and lands on the floor. After you have analyzed its motion, you must predict where and when the ball will land when shot at a different angle.

Here's the basic setup:

I will set up a single cannon (one of the ballistic pendulum devices) in the middle of the room, on top of a table. I will tilt the barrel of the gun by an angle theta = 45 degrees and fire the cannon at its "long range" setting. I will fire the cannon three times so that the ball falls onto a piece of paper in a cardboard box. One student from each group will measure the duration of flight t during each trial, and we'll write all the measurements on the board. Then, each group independently must

  1. using the height H and total length L, determine the speed v0 at which the ball leaves the cannon, and the time of flight t. Show all your work.

  2. compare this value of t with the measurements. Discuss.

  3. compute the uncertainty in the initial speed v0

  4. predict that if I change the angle of the barrel to theta = 65 degrees, If you have the time, compute the uncertainty in these values.

Near the end of the class period, I will make the shot at the new angle of theta = 65 degrees, and we'll see how well you do.

Creative Commons License Copyright © Michael Richmond. This work is licensed under a Creative Commons License.