Ping Pong Vacuum Cannon

A sealed tube is evacuated and a ping pong ball is placed near one end. When the near seal is ruptured, atmospheric pressure accelerates the ball down the evacuated tube with negligible air resistance, allowing extreme speeds that can puncture cans and thin plywood. This demonstration highlights gas pressure, Newton’s laws, and the role of drag.

1. Refer to links below for construction, setup, and operating instructions.

Supersonic ping pong balls…vacuum and compression cannon combination. PART TWO - Homemade Science with Bruce Yeany:

Supersonic Ping Pong Balls Launcher?! Purdue University Physics Experiment - Purdue University:

📄 Vacuum Cannon Drives Ping Pong Ball at Supersonic Speed - Bill WW: https://www.instructables.com/Vacuum-Cannon-drives-ping-pong-ball-at-supersonic-/

📄 Vacuum Cannon - Harvard: https://sciencedemonstrations.fas.harvard.edu/presentations/vacuum-cannon

• Use high-speed video (behind a protective shield) to compare acceleration and exit speed under different vacuum levels.
• Replace destructive targets with soft catch boxes (e.g., dense foam) to capture the ball for momentum studies.
• Convert to a purely observational demo behind a transparent ballistic barrier and use a photogate or timing screens for non-destructive speed measurement.

• Treat this as a high-energy projectile launcher; it can be as dangerous as a firearm at close range.
• Use a certified ballistic shield in front of the muzzle and a solid backstop behind the target; keep all people strictly out of the line of fire and behind barriers.
• Wear ANSI-rated eye/face protection and hearing protection; enforce PPE for everyone in the room.
• Operate only in a controlled lab space with remote triggering; never place any body part in front of or behind the tube once under vacuum.
• Use schedule-rated pressure/vacuum-compatible tubing and fittings; inspect for cracks and never exceed manufacturer limits.
• Evacuate and vent slowly; unexpected ruptures can occur during pump-down. Keep hands clear of seals and use long tools to initiate rupture.
• Secure the tube to a rigid mount to prevent recoil or whipping; restrain vacuum hoses and cables.
• Prohibit improvised targets (glass, batteries, aerosols) and eliminate ricochet hazards.
• Establish a written range protocol (clear range calls, countdown, misfire procedures) and maintain a safety perimeter.
• Supervision by qualified personnel is mandatory; follow all institutional and legal requirements for high-energy demonstrations.

• Why does removing air from the tube dramatically increase the achievable speed? (It eliminates drag inside the tube, so the net force is roughly atmospheric pressure times ball area.)
• What ultimately limits the maximum speed? (Finite pressure differential, membrane rupture dynamics, ball/tube leakage and deformation, and speed of sound constraints at the muzzle.)
• How could you measure exit velocity safely and accurately? (Photogates, break-beam timing screens, or a ballistic pendulum behind shielding.)
• Why does the ball slow rapidly after leaving the tube? (Air drag increases dramatically; Reynolds number and compressibility effects dominate in free air.)
• How would weaker vacuum, different membrane materials, or a longer tube change performance? (Lower vacuum reduces net force; tougher membranes delay/alter pressure rise; longer tubes allow more acceleration up to drag/leak limits.)