- Glenn Research Center
- Physical Science
- Exploring Engineering and Technology
- 030 min(s)
- 060 min(s)
The Space Shuttle, the most complex machine ever built, weighs almost four and one-half million pounds. How do you suppose NASA lifts the parts to join them together and then gets the whole assembly up onto the launch pad? Would you think it can be done with technology that goes back thousands of years?
This module is appropriate for video conference AND web conference presentation.
Simple machines have been used for thousands of years and yet are still the basis for our modern complex machines. Simple machines are devices that are generally used to multiply force at the expense of distance, although the reverse is sometimes desired. The event will discuss and demonstrate simple machines, cover forces, ratios, and mechanical advantage, and demonstrate how complex machines are combinations of simple machines
The learners will discuss why we use machines and what they do for us.
|The learners will examine the inputs and outputs of a familiar machine and discuss this in the broader context of the nature forces.|
|The learners will explain the application of the multiplication of forces to the problem of raising a jeep, particularly using an inclined plane. they will also explain the different types of simple machines and how they are alike.|
|The learners will apply these ideas to a number of types of simple machines and demonstrate how forces are changed. they will also discuss NASA applications of simple machines.|
|The learners will evaluate their learning by suggestion solutions to a problem by the application of simple machines.|
Sequence of Events
How does changing the length of a lever affect your ability to lift something heavy? What is the best shape to make a wedge if you want to split a stone?
A great way to begin an investigation of simple machines is to carry out the investigations at Aspire's "Simple and Complex Machines" These computer-based activities have students collect information on force and distance on various machine and construct graphs.
How much do you know about simple machines?
Axle: the pin, bar, shaft, or the like, on which or by means of which a wheel or pair of wheels rotates. Axles on the crawler that carries the Shuttle to the launch pad must be very strong to carry over 4.5 million pounds.
Force: an influence on a body or system, producing a change in movement, usually defined as a push or pull. Simple machines can increase forces.
Inclined plane: a plane surface, such as a ramp or a blade, set at an acute angle to a horizontal surface. The Space Shuttle is carried up a long inclined plane to get it onto its launch pad.
Lever: a rigid bar that pivots about one point and that is used to move an object at a second point by a force applied at a third. Many of the 1,000 switches on the Space Shuttle are levers.
Mechanical advantage: the ratio of output force to the input force applied to a mechanism. When a simple machine increases a force the mechanical advantage is greater than one.
Pulley: a wheel, with a grooved rim for carrying a line, that turns in a frame or block and serves to change the direction of or to transmit force, as when one end of the line is pulled to raise a weight at the other end. The different parts of the Space Shuttle are joined together after having been lifted by pulleys.
Ratio: an expression of the relative size of two numbers by showing one divided by the other. Mechanical advantages of simple machines are ratios.
Screw: a simple machine of the inclined-plane type consisting of a spirally threaded cylindrical rod that engages with a similarly threaded hole. Bolts and screws hold much of the Space Shuttle together.
Wedge: a piece of material, such as metal or wood, thick at one edge and tapered to a thin edge at the other for insertion in a narrow crevice, used for splitting, tightening, securing, or levering. The sharp edges of scissors used to cut the material to make space suits are wedges.
Wheel: a circular frame or disk arranged to revolve on an axis, as on or in vehicles or machinery. The main wheels on the Space Shuttle weigh 205 pounds each.
Work: force times the distance through which it acts. When simple machines increase force they decrease distance so the amount of work always stays the same. The amount of work to get the Shuttle up on its launch pad is the same whether you bring it up a long ramp or lift it straight up. Using the ramp requires more distance, but less force.
At the beginning of this video conference the presenter will use a model of a jeep and a book and ask the question as to how much effort it would take to lift the jeep on top of the book. A spring scale will be used to demonstrate the amount of force to raise the jeep. Then the presenter will ask the question "Is there an easier way to get the jeep up onto the book"?
After taking suggestions the presenter will use a ramp to drive the jeep up onto the book and measure the effort required with the spring scale. Then a ruler will be used to measure the vertical and ramp distances and compare this ration to the ratio of forces.
With the introduction that a ramp is a simple machine called an inclined plane, the presenter will discuss a general notion of what a machine is and how they can take a variety of inputs and produce a variety of outputs. The students will be asked to think about the machines that they find in their homes and what kinds of inputs and outputs there are in terms of energy.
The presenter will then discuss the nature of most complex machines being made of combinations of simple machines, which modify the input force to make it larger or smaller by trading force for distance. The concept of work as a product of force times distance will be presented and calculations will be used to show that even though machines make it possible to multiply forces they always do the same amount of work. Then he will ask the students to list all the simple machines, grouping them by related means of operation.
The presenter will then demonstrate models of the simple machines, showing how force and distance can vary with each. Students will be asked to think of ways each machine is used as they are demonstrated. Some of the questions asked the students may be like the following:
What would happen if both lever arms were the same length? What would limit the ability of a lever to provide a mechanical advantage? Do all pulleys increase force? What happens when pulleys are combined? What makes a chisel able to carve stone? What are the simple machines in a pair of scissors? Which are stronger, screw top bottles or corked bottles? Why?
Finally the presenter will show how NASA uses simple machines for a number of complex tasks such as stacking the Shuttle components together using pulleys or getting the assembly up onto the launch pad up an inclined plane.
Have your ideas about simple machines changed? Do you think you use simple machines every day? Do you think you could go a whole day without using a simple machine?Take the post-conference quiz to measure how your ideas have changed.
Did Leonardo DaVinci know about simple machines? How did the large heads on Easter Island get moved?
You can answer these questions and find out more about simple machines at Educational Technology Center at Kent State University (KSU) as well as at the National Science Digital Library - Simple Machines
Grade specific lesson plans are available.
NSTA Science Content Standards 5-8:
PHYSICAL SCIENCE CONTENT STANDARD B
MOTIONS AND FORCES
- The motion of an object can be described by its position, direction of motion, and speed. Simple machines can be used to alter the motion of objects, especially direction.
NSTA Science Content Standards: 9-12
PHYSICAL SCIENCE CONTENT STANDARD B
MOTIONS AND FORCES
- Objects change their motion only when a net force is applied. Laws of motion are used to calculate precisely the effects of forces on the motion of objects. The magnitude of the change in motion can be calculated using the relationship F = ma, which is independent of the nature of the force. Whenever one object exerts force on another, a force equal in magnitude and opposite in direction is exerted on the first object. Simple machines can be used to multiply forces.
NCTM Principles and Standards for School Mathematics: 6-8
Numbers and Operations Standard for Grades 6-8
- Understand the use of ratios and proportions to represent quantitative relationships