Hero's Engine (Rena Benor)


Rena Benor 


Steam engine    Newton's 2nd and 3rd law of motion.
Turbines    Torque


Motion and Forces
1. Newton’s laws predict the motion of most objects. As a basis for understanding this concept: a. Students know how to solve problems that involve constant speed and average speed.
c. Students know how to apply the law F=ma.  (Force=mass x acceleration)  to solve one-dimensional motion problems that involve constant forces (Newton’s second law).
d. Students know that when one object exerts a force on a second object, the second object always exerts a force of equal magnitude and in the opposite direction (Newton’s third law).

Materials needed

Hero's engine
heat source
safety glasses


Fill the flask with a small amount of water. Wear safety glasses. Put a heat source underneath it.  As the water starts to boil, the flask will start to rotate.


Hero's Engine is today a generic name for any device which propels itself by shooting steam from one or more orifices. These devices are also known as Eolipiles. It is considered to be the first recorded steam engine or reaction steam turbine.

After filling the sphere with water, a flame is applied to it until the water boils, and the device begins to rotate.

Having oppositely bent or curved nozzles projecting from it. When the vessel is pressurized with steam, steam is expelled through the nozzles, which generates thrust due to the rocket principle as a consequence of the 2nd and 3rd of Newton's laws of motion.

The thrusts combine to result in a rotational moment or torque, causing the vessel to spin about its axis. Aerodynamic drag and frictional forces in the bearings build up quickly with increasing rotational speed (rpm) and consume the accelerating torque, eventually canceling it and achieving a steady state speed.


  1. What must occur before the Hero's engine spins?
  2. What does the shape and direction of the arms have to do with its motion?
  3. How is this translated for today's machines?

Everyday examples of the principles illustrated

A steam engine is a heat engine that performs mechanical work using steam as its working fluid.Water turns to steam in a boiler and reaches a high pressure. When expanded through pistons or turbines, mechanical work is done. The reduced-pressure steam is then condensed, and it is pumped back into the boiler. Early devices were not practical power producers, but more advanced designs producing usable power have become a major source of mechanical power over the last 300 years, his power source would later be applied to prime movers, mobile devices such as steam tractors and railway locomotives. The steam engine was a critical component of the Industrial Revolution, providing the power source to propel modern mass-production manufacturing methods. Modern steam turbines generate about 90% of the electric power in the United States using a variety of heat sources.

F = ma lets us work out the forces at work on objects
by multiplying the mass of the object by the acceleration of the object.

The force at work on a Formula 1 car as it starts a race!

If the F1 car has a Mass of 600kg and an Acceleration of 20m/s/s
then we can work out the Force pushing the car by multiplying
the Mass by the Acceleration like this 600 x 20 = 12000N

F = ma is the second law of motion proposed by Sir Isaac Newton.




Youtube link of classroom model. 
Youtube link of Yale experiment.




 Click here for instructions on :Building a Hero's engine
                                                 Building a Hero's engine2