Table of Mechanics Demonstration

List of Mechanics Equipment & Supplies

Lecture Demonstrations

Rocket Tricycle, 1N22.10

Topic and Concept:

Location:

RocketTric01-400.jpg

Abstract:

Dual-mounted CO2 fire extinguishers are on the back of a tricycle.

Equipment

Location

ID Number

Rocket Tricycle

(ME) Floor Item, East Wall

5 lb CO2 Cylinders

(ME) Floor Item, Northeast corner by column

Hand Air Pump

FM, Bay B4, Shelf #1

Important Setup Notes:

Setup and Procedure:

  1. Make sure the tricycle's three tires are filled to the specified air pressure.
  2. Make sure there are(is) (a)filled CO2 fire extinguishers on the back basket of the tricycle. If replacements are necessary, switch out the old fire extinguishers by loosing the black knobs which keep the main holding bracket in place. After switching the new extinguishers in to the mount, the holding bracket needs to be tightened again.

  3. Be sure the release handles on the extinguishers are situated beneath the push-down lever such that the nozzles are directed away from the rider.
  4. Situate the tricycle so that it has at least 50 ft for cruising distance (25 ft if using one extinguisher).
  5. When ready, push down the lever from the right-hand side to engage propulsion.
  6. A few trial runs are recommended.

Cautions, Warnings, or Safety Concerns:

Discussion:

From the viewpoint of Newton's third law, when a body exerts a force on another body, that body then exerts a force equal in magnitude but opposite in direction on initial body. Applied to our rocket-powered tricycle, the CO2 gas is pushed out of the extinguishers by a pressure differential, The force on the gas molecules originates within the extinguishers which are attached to the tricycle. The gas then pushes back on the extinguishers causing the tricycle to move forward.

From the viewpoint of the conservation of linear momentum, our system is initially at rest (p=0). When the CO2 gas is shot out from the extinguishers, the constituent molecules carry with them a momentum in the reverse direction (pCO2 = mCO2 * vCO2). To conserve momentum, the tricycle must gain the same amount of momentum in the forward direction. While the mass of the CO2 ejected is relatively tiny compared to that of the tricycle plus the rider, this average speed of the molecules is very high compared to that which the tricycle will gain.

RocketTric02-250.jpg

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RocketTric04-250.jpg

RocketTric05-250.jpg

RocketTric06-250.jpg

RocketTric07-250.jpg

RocketTric08-250.jpg

RocketTric09-250.jpg

Videos:

References:

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