This design of a marble launcher uses a plunger that is pulled back inside of the barrel so that a compression spring begins to compress and create potential energy, once released the spring drives the plunger through the barrel which forces the marble out of the barrel.

Supplies

The materials required to create this type of a marble launcher are:

- 5 inch compression spring

- 2 10 inch 2x4 boards

- 10 inch pvc tube with a half inch diameter and a cap

- 10 inch metal rod with threads on both sides

- 2 lock nuts and a washer with half inch diameters

- 2 screws, glue, duct tape and a drill

Step 1: Step 1: the Barrel

The first part in creating the barrel is applying the cap to one end of the 10 inch pvc pipe, this can be applied using the proper glue for pvc. The cap must have a hole drilled in it with a fourth of an inch diameter. Another hole with the same dimensions should be drilled in the side of the barrel 2 inches away from the open end.

Step 2: Step 2: the Plunger

Take the threaded 10 inch metal rod and lock the washer on the end by using the 2 lock nuts.

Step 3: Step 3: Assembly

Take the 5 inch spring and put it inside of the barrel. Then take the plunger and put it inside of the barrel so that the washer catches on the spring while the other end runs out of the hole in the cap. Next create a handle with duct tape on the other end of the rod so that you have more grip and so the rod does not fly out of the barrel after releasing it. Lastly, screw the barrel onto one of the wood pieces using the hole on the side of the barrel, attach this board to the other board with another screw in the center of the boards.

Step 4: Projectile Motion Calculations Based Upon Launch Performance

This launcher was tested by hitting targets at 3 different distances.

Time formula t=√2(y-xtanθ)/g Initial velocity formula s=ut+1/2at²

Trail 1 the launcher hit a target 4.5 meters away at a .28 meter launch height and a 25 degree launch angle, using the time formula time was .61 seconds and using the initial velocity formula the marble left the barrel at 7.4 m/s.

Trail 2 the launcher hit a target 4 meters away at a .28 meter launch height and a 25 degree launch angle, using the time formula time was .57 seconds and using the initial velocity formula the marble left the barrel at 7.0 m/s.

Trail 3 the launcher hit a target 3.5 meters away at a .28 meter launch height and a 25 degree launch angle, using the time formula time was .53 seconds and using the initial velocity formula the marble left the barrel at 6.6 m/s.