Simple Machines: Top 10 Questions

January 2014

Thanks to Dr. Kathryn Devine, Assistant Professor of Physics, College of Idaho; and Dr. John Gardner, Director, CAES Energy Efficiency Research Institute, Boise State University for the answers.

1: Why are they called simple machines?

Most of the machines we work with are complicated, but they are made up of a few simple building blocks. These building blocks are the six machines. The six machines are the lever, the wedge, the pulley, the inclined plane, the screw, and the wheel and axle. Pretty much everything we have is some combination of these machines. (From Magenta at Garfield Elementary School in Boise)

2: Who made the first simple machine?

We do not know who made the first simple machine. Evidence of wheels and axles goes back at least 5,000 years, and wedges are known to have existed before that. Simple machines have been around for thousands of years. They originated during a time when there were no communications between the many different cultures using them. (From Veta at Basin Elementary School in Idaho City)

3: How is work measured?

There are different types of work, and there are different types of instruments to measure work. Physicists use a unit called joules to measure energy. You also know about calories, which are units used to measure the energy of food. Physical work, pushing a block a certain length, is a force multiplied by a distance. Work is a combination of two different physical things: force and distance. In terms of electricity, we calculate volts and amps. So, any time you are talking about work or energy, it's really two different things considered together. (From Natalee at Garfield Elementary School in Boise)

4: What is the most useful simple machine?

It depends on what your need is. They are all very useful and one is not anymore important than the other. The most common machine is probably the wheel. (From Drew at Riverside Elementary School in Boise)

5: How do you make a simple machine?

The easiest simple machine to make is the lever. You need a long, rigid bar and a fixed object to lean it against. That way the bar can pivot around the fixed object. Another easy simple machine to make is the wedge. Any small block of wood or metal that tapers to a point can be used as a wedge. Wheels are harder to make because they have to be perfectly round. (From Shelby at Kamiah Elementary School in Kamiah)

6: How big can a machine get?

A machine can be as big as you want it to be. The sky is the limit. The bigger the machine, the more expensive it is to make. So you would only want to make it as big as you need it to be. It's more challenging to make these machines really, really small, like the parts used in a watch. (From Audrey at Riverside Elementary School in Boise)

7: How does a lever work?

Energy, or work, is a force through a distance. A lever gives you a way of exerting force at another location. You push a lever at one end and it exerts force at the other end. The fulcrum is the pivot point. The amount of force exerted at the other end of the lever is dependent on the distance between the fulcrum and where the force originates. The greater the distance, the less force is exerted at the other end. The smaller the distance, the greater the force is at the other end. (From Ashton at Basin Elementary School in Idaho City)

8: When my teacher pulls her map down, what simple machine is she using?

She is primarily using the wheel and axle because the map wraps around a tube. The map can lock in place and spring back, so there would also be other simple machines involved also, like levers. (From Isabella at Cynthia Mann Elementary School in Boise)

9: Who made the pulley?

The oldest record we have of the pulley is from the third century B.C. by Archimedes. The pulley may have been around way before that, but he is the first one to have written it down in a way to survive to modern times. (From Sam at Basin Elementary School in Idaho City)

10: Do some simple machines only come from some cultures?

The wheel, wedge and lever were developed independently across many cultures thousands of years ago mainly because they are simple to build and invent. We're unsure of who invented the screw and pulley as they would have been trickier to build and would have required more ingenuity. (From Ben at Garfield Elementary School in Boise)

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