Trajectories Lab

All students must wear eye goggles while in the lab.

Part 1

Determine the muzzle (exit) velocity of the cannon

n  Fire the cannon horizontally-medium range setting.

n  Determine the cannon's  exit velocity when it leaves the barrel of the cannon.

n  This can be calculated by measuring:

     ð Projectile height above the floor (measure to center of cannon barrel)

     ð Distance the projectile travels over the floor-use plumb bob to mark start point. Make 3 shots and find

          the average of the distances.

n  Then solving:

     ð y = y₀ + v_y0t + 1/2gt²   for t    Note: v_yo = 0. Why?

     ð Solve x = x₀ + v_x0t + 1/2a_xt²   for v_x0

Part 2

Compare theory (equations) with experimental results

Section A: During the lab

Try to hit a target that I place on the floor - at a distance of about 4.5 meters.

Select a "shooter", a "measurer", and an "angle calculator/setter"

n  Pick an angle and try to hit the target.

n  Fire the cannon at this angle - you get two shots with 2 different angles.

n  Measure the distance travelled in each case - note the angle and distance for the closest shot. This will be used in section B.

n  Perhaps give bonus points if a team hits the target.

Section B: After the lab

n  For the angle used to obtainthe closest shot to the target and the calculated muzzle velocity from Part 1, calculate the distance to where the ball

      should land.

n  You may want to use the following equations:

     ð y = y₀ + v_y0t + 1/2a_yt²   to solve for t  Note: you will need to use the quadratic formula       v_y0 = v₀sinq

     ð x = x₀ + v_x0t + 1/2a_xt² to solve for x    Note: a_x is 0. Why?  v_x0 = v₀cosq

n  Compare this with the actual distance. Provide possible explanations for any discrepancies (calculated versus actual distance).

Turn In

n  For Part 1: All data and calculations used to determine the muzzle velocity and results of the target practice (how much missed if any).

      Describe your approach to select a firing angle to hit the target and how adjusted for the second shot.

n  For Part 2: The calculated distance based on selected angle and exit velocity. Provide possible rationale or explanations for any inaccuracies

      in part 2B (actual distance from Part 1 compared with calculated distance from Part 2).