Demonstration Description: A monkey is suspended from a rod at one end of the lecture table (or tall stand). The monkey begins falling at the same instant a gun fires a golf ball from the other end of the table. Projectile and target meet in mid-air.
Demonstration Instructions: Materials:
1. Spring loaded golf ball gun with trigger switch at muzzle.
2. Monkey doll
3. Solenoid marked "monkey" with 10 m cable pair.
4. Hewlett-Packard 6299A power supply
5. Knife switch (used to defeat the muzzle switch)
6. Golf balls
7. 12' support post
8. Table clamp for above post
9. 90° rod to rod clamp
10. Banana cables
11. Gun cocking bar
13. 12" C-clamp
1. Clamp the solenoid to the 12' post using the 90° clamp. Wrap the cable around the post a few times.
2. Clamp the above assembly to the far right end of the lecture tables using the table clamp.
Position so that solenoid is on side of post facing left.
3. Clamp the golf ball gun to the far left end of the lecture tables with one C-clamp.
4. Clamp the knife switch to the edge of the table near the gun.
5. Place the power supply next to the knife switch. Connect the power supply to the knife switch, golf ball gun and the solenoid wires according to the schematic.
6. Turn on power supply, set to 10V, close knife switch and attach the monkey's head to the solenoid. It should hold firmly enough so it won't fall. Knife switch must remain closed until gun is cocked.
7. Adjust aim of gun to point directly at hanging monkey.
8. Cock the gun with the rod. Load golf ball. Knife switch can now be opened without the monkey falling. If knife switch is not opened before operation, monkey will not fall when triggered by the gun.
9. Fire the golf ball by releasing the lever on the back of the gun.
10. The golf ball should hit the metal plate on the monkey's body. If not, make adjustments to the position of the gun until operation is reliable.
1. Turn on power supply and check to see it is set to 10V.
2. Close knife switch. Switch must remain closed until gun is cocked. DO NOT LEAVE CLOSED FOR MORE THAN 5 MINUTES.
3. Climb ladder and attach monkey to solenoid. Move ladder away.
4. Cock golf ball gun with the rod.
5. Insert golf ball.
6. Check aim of gun (do not actually adjust)
7. OPEN THE KNIFE SWITCH.
8. Fire the gun by moving the trigger lever sideways.
9. Ball should hit falling monkey. If monkey does not fall, knife switch was not opened.
REMEMBER TO RELEASE THE KNIFE SWITCH AFTER THE DEMONSTRATION.
THE SOLENOID WILL OVERHEAT AND BURN.
The horizontal motion of the golf ball and its vertical motion are independent of one another, but combine to give the golf ball a parabolic trajectory. The ball and monkey fall at the same rate under the force of gravity. It can be shown that at some time, both the x and y coordinates of the ball and monkey will be equal, indicating that the monkey has been shot. As long as this time occurs before the monkey has hit the ground, the monkey will be shot.
Row I; Stand, against window; power supply, Row V
See page 86, University Physics, for information regarding the monkey and gun problem.
Young, Hugh D., Roger A. Freedman, and A. Lewis Ford. Sears and Zemansky's University Physics: With Modern Physics, 12th ed. San Francisco: Pearson Addison-Wesley, 2008.