Section 2 Simple Machines I Types of simple

Section 2 Simple Machines

I. Types of simple machines A. Simple Machine-a machine that does work in one motion. 1. There are six types of simple machines.

B. Levers – bar that is free to turn about a fixed point. 1. The fixed point is called a fulcrum Resistance arm Effort arm fulcrum Resistance Force

2. Three classes of levers:

What Class? Third Class First Class Second Class

C. Pulley – a grooved wheel with a rope, chain, or cable running along the groove. 1. Fixed pulley-attached to a fixed object.

D. Wheel and Axle – two wheels of different sizes that rotate together. 1. usually the effort force is applied to the larger wheel.

E. Inclined Plane – sloping surface that reduces the amount of force required to do work.

F. Wedge – inclined plane with one or two sloping sides

G. Screw – inclined plane wrapped in a spiral around a cylindrical post.

Mechanical Advantages of Simple Machines

II. Mechanical advantage (MA) A. A ratio of the output force and the input force 1. MA greater than one – multiplying the input force 2. MA less than one – increase distance or speed.

B. Lever Length of effort arm MA = Length of resistance arm MA = Le Lr

C. Inclined Plane MA = length of slope height of slope l h Effort distance MA = Resistance distance

D. Pulley 1. Fixed pulley, MA = 1 E. Wheel & Axel MA = Radius of wheel Radius of axle rw ra