Re: Fan and Propellor Blades in Ed Head Simple Machines Games

Author: Bruce, ComPADRE Dir
Posted: Jan 25, 2013 10:56PM UTC

Hi Eve,

The way they are using the definitions, a wedge is used for splitting or cutting through solid objects or materials and the inclined plane is used to move materials along the inclined surface with less force than is necessary to move it directly. So the incline, or pitch, on the fan blade and propeller makes it easier to push the air or water than trying to push with a surface perpendicular to the direction of motion.

Of course, these definitions are not precise and you can find different definitions, and different numbers of simple machines, in different places. The important physics is WHY the simple machines make doing jobs easier.

Hope that helps.
Bruce

• Each force acts on one particular object and has both strength and a direction. An object at rest typically has multiple forces acting on it, but they add to give zero net force on the object. Forces that do not sum to zero can cause changes in the object's speed or direction of motion. (Boundary: Qualitative and conceptual, but not quantitative addition of forces are used at this level.) (3)
• For any pair of interacting objects, the force exerted by the first object on the second object is equal in strength to the force that the second object exerts on the first, but in the opposite direction (Newton's third law). (6-8)

• When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object. (6-8)

• Modeling in 3–5 builds on K–2 experiences and progresses to building and revising simple models and using models to represent events and design solutions. (3-5)
  • Use models to describe phenomena. (5)

• 3-5: 4F/E1bc. The greater the force is, the greater the change in motion will be. The more massive an object is, the less effect a given force will have.
• 6-8: 4F/M3a. An unbalanced force acting on an object changes its speed or direction of motion, or both.

• 3-5: 11B/E3. A model of something is similar to, but not exactly like, the thing being modeled. Some models are physically similar to what they are representing, but others are not.
• 6-8: 11B/M4. Simulations are often useful in modeling events and processes.

This activity is an animated introduction to simple machines.   Designed for Grades 3-6, it helps children gain understanding of the different types of simple machine they encounter in their kitchens, garages, bedrooms, and bathrooms. Additionally the site provides a glossary of important terms, lesson plans and a teacher's guide.

• Physical Sciences K-8 Applications of Newton's Laws Unit