PASCO ME-6831 Ballistic Pendulum_Projectile Launcher - Manual (Page 13)

®
M o d e l N o . M E - 6 8 3 0 , M E - 6 8 3 1 B a l l i s t i c P e n d u l u m T h e o r y
0 1 2 - 0 5 3 7 5 C 9
Repairing the Plumb Bob
If the string breaks that holds the plumb bob on the protractor of the
Launcher, replace it with an equal length of nylon thread (such as the thread
included in the ME-6802 Launcher Spares Kit). Make sure that the replace-
ment string is long enough so that when the Launcher is inclined at an angle
of 50°, the string extends well below the corner of the Launcher. Carefully
thread the replacement string through the small hole at the vertex of the pro-
tractor and tie a triple knot at that end of the string. To put the plumb bob
onto the string, thread the string through the hole in the center of the plumb
bob and tie a triple knot in that end of the string.
Installing the 2-D (two dimensional) Collision Accessory
Introduction
The 2-D (two dimensional) Collision Accessory is a plastic
bar with a thumbscrew and square nut. The bar has a post
and you can balance a second ball on the post in front of the
muzzle. When the launched ball collides with the second
ball, they experience a two dimensional (2-D) collision.
Assembly
To assemble the Collision Accessory, insert the thumb-
screw through the hole in the plastic bar and screw the
square nut onto the thumbscrew. Leave the square nut loose
on the thumbscrew until you install the Collision Acces-
sory onto the Launcher.
To install the Collision Accessory onto the Launcher, slide
the square nut into the T-shaped slot on the bottom side of the barrel. Adjust the position of the Collision Acces-
sory and then tighten the thumbscrew. Place a ball on the top of the post, loosen the thumbscrew slightly, and
rotate the Collision Accessory to one side or the other until the ball on the post is in a place where it will be hit by
the launched ball at the angle that you want.
Expectations for the Projectile Launcher
• The muzzle speed will vary slightly with angle. The difference between muzzle speed when shot horizontally
versus vertically can be between zero to eight percent, depending on the range setting.
• Although the muzzle end of the Projectile Launcher does not change height with angle, it is about 30 centime-
ters (12 inches) above table level. If you desire to show that projectiles fired with the same muzzle speed but
at complementary angles will have the same range, you need to shoot to a horizontal target that is at the same
height as the muzzle.
• The scatter pattern of projectiles with the Projectile Launcher is minimized when the Projectile Launcher is
securely clamped to a sturdy table. Any wobble in the table will show up in the data.
• The angle of inclination can be determined to within one-half of a degree.
Expectations for the Ballistic Pendulum
• Angles reached by the swinging pendulum should be repeatable to within half a degree.
Plumb bob
Tie a triple knot
in the end.
Thread through
the hole.
Make the string
long enough.
Vertex
Repairing the Plumb Bob
50°
Projectile
Launcher
barrel
Square
Nut
T-slot
Thumbscrew
2-D Collision Accessory