PASCO Monkey and Hunter, 1D60.30

Topic and Concept:

• Motion in Two Dimensions, 1D60. Projectile Motion

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Location:

• Cabinet: Mechanic (ME)

• Bay: (A5)

• Shelf: #1

Abstract:

This is Pasco's version of "Shoot the Target". A target (in this case a stuffed monkey) is released about 2 meters above the table top as soon as a projectile (a Ball) is fired. The ball then hits the target in midair given that the system is properly aligned.

Important Setup Notes:

• This demonstration can take up to 10 minutes to setup and align.

• This demonstration will require practice - The failure rate for this demo is ~5%.

• Do not connect monkey to magnet until ready for use - metal attachment tends to become magnetized over periods of 20 minutes which inhibits the dropping mechanism.
• Too much light incident on the photogate will cause the triggering mechanism to malfunction and not release the target.

Setup and Procedure:

1. Mount the support rod, with the Drop Box at the top, to one end of the lecture bench.
2. Roughly align the Long Range Projectile Launcher on opposite end of lecture bench and with 2 C-clamps, clamp it in place. (The further apart, the higher the target must go.)
3. Connect the power cord, telephone cord, photogate to the Control Box.
4. Make sure the photogate is correctly positioned on the Long Range Projectile Launcher so that the ball will trip the gate with fired.

5. Make sure the triggering system is not yet armed - The red light should be off. Otherwise, the photogate will trigger a premature drop of the monkey.

Alignment & Testing:

1. Use a tall ladder and place either the Monkey or the Target onto the electromagnet pin, under the Drop Box between the two white pins.
2. Look up through the bottom of the launcher, (not down the launcher). Use the two cross-hairs located in the bottom of the launcher barrel to align the launcher with the monkey.
3. Roughly align the launcher, tighten set screws, and firmly clamp the base to the table with a pair of "C"-clamps.
4. Use a mallet to adjust the launch's azimuthal and vertical angles of Projectile Launcher, if necessary.
5. Load the launcher with a (yellow)Projectile Ball by using the 28 cm black plunger rod to push the projectile into the barrel to the desired spring setting, usually to the third stop or click. This is demonstrated in the video linked below. There are three such settings. The spring will click each time a new setting is reached.

6. Arm the triggering system by flipping the switch on the Control Box - The red light should be on.

7. Test fire by pulling the release cord to verify that the setup is properly aligned. If not, use a mallet to readjust the launch's azimuthal and vertical angles of Projectile Launcher.
8. Reattach the monkey to the electromagnet and retest. If alignment is still bad, repeat above procedure.
9. Note: Aiming slightly into the 1st quadrant may help.
10. Once alignment is achieved, use the same above steps (minus the alignment adjustments) to perform the demo.

Cautions, Warnings, or Safety Concerns:

• DO NOT look down the barrel of the projectile launcher - a spontaneous launch could take your eye!
• Take care to not aim the projectile launcher at or near the audience; also keep in mind the possible post-contact trajectories of the projectile.

Discussion:

The Pasco projectile launcher is carefully aimed at a stuffed monkey by looking through the bottom of the launcher and using the cross-hair to target the monkey. The target is held up by an electromagnet which is coupled to the launcher via the PASCO interface and a photogate. The instant the projectile is launched through the photogate, the monkey is dropped. Since the monkey and the projectile are falling at the same rate, the projectile will hit the monkey in midair. The launcher has 3 spring settings so that you can show the students that this is independent to the particle's velocity. Please note that the first spring setting is very week and is for close range or the monkey must be set much higher then what is shown here.

Videos:

• PASCO Monkey and Hunter, 1D60.30

• Lecture Demonstration's Youtube Channel

References:

• PASCO item page

• Clinton Sprott

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