Newton’s Laws of Motion

Are you familiar with Newton’s three laws of motion?

Newton's Cradle

In 1687 Sir Issac Newton published his works entitled Philosophiæ Naturalis Principia Mathematica. As intimidating as that may sound it is simply Latin for “Mathematical Principles of Natural Philosophy.” In this work he compiled three laws that are now renownedly known as Newton’s Laws of Motion. In this blog we will consider what the three laws are, why they matter and some modern-day examples to make them relatable.

  1. Newton’s First Law of Motion

An object at rest tends to stay at rest and an object in motion tends to stay in motion. However either can be changed due to an application of force.

This law is essentially Galileo’s concept of inertia and is known simply as the Law of Inertia. Newton stated this law to set the parameters for his next two laws. I’ll use a Fidget Spinner for an example. Before spinning, the object would likely not start spinning on it’s own! However, after spinning one, it would continue to spin forever if it were not for the effects (forces) of friction and gravity. It would be interesting to see an astronaut try this experiment while in space! 

 

2. Newton’s Second Law of Motion

Force equals Mass times Acceleration F=ma

This law explains the connection between the mass of an object, the acceleration and the resulting force. This equation also works backwards to determine the mass or acceleration of an object. For an example let’s use two vehicles on a crash-test course to determine their differences in force during impact. Let’s say Vehicle 1 is a Military Hummer with a weight of 7,700 lbs and Vehicle 2 is a Smart Car with a weight of 3,000 lbs. It seems we all know which would have more force but how do we reach that conclusion? Can Vehicle 2 impact with more force than Vehicle 1? Newton’s Second Law tells us. Lets take a look. Vehicle 1 weighing 7,700 lbs traveling at 60 mph will hit the wall dealing a force of 462,000 N. Vehicle 2 traveling at the same speed will only deliver 180,000 N of force. For Vehicle 2 to exert the same amount of force on the wall it would need to be traveling at 154 mph. That’s over twice as fast!

 

3. Newton’s Third Law of Motion

For every action there is an equal and opposite reaction

This Law is pretty easy to understand. Newton is telling us that for each and every force between two objects there is another force in the opposite direction of equal magnitude. An example of this is Newton’s Cradle. The cradle holds 5 balls of equal weight and size suspended from a foundation. If one ball is lifted and released it will hit the other four motionless ball and stop. However, the force will travel through three of the balls and cause the fourth to swing into the air as if you had pulled it up like the first! This scientific gadget can be used in different ways to yield different results (such as lifting two, three or even four of the balls). However, the law still remains the same. What we learn is that the ball that stops exerts its force toward the other four while at the same time the four exert a force on it.

 

Newton's Cradle

 

Now you have it! We really hope you enjoyed learning with us. Please come back to find more scientific knowledge and experiments! And feel free to share this page with any interested friends, family or students!

Teaching Wind Power

The interest in renewable energy has increased greatly. The US currently produces enough wind energy to power 14 million homes. Approximately 2% of our energy comes from wnd, which is double from just 3 years ago. many beleive that in 2030, 15-20% of our energy will come from wind.

The reason for the growth is partially associated with new government regulations concerning our impact on the environment. Federal and local governments are receiving pressure from voters to find alternative sources. Experts believe that if the 2030 scenerio occurs, we would reduce carbon dioxide emissions by 7600 metric tons and create 200,000 jobs.

Windmills have been around for centuries to pump water and grind seeds into grain. A wind turbine is an advancement that turns an electrical generator. The force of the wind, turns the blades. the rotor turns and spins a driveshaft that is connected to an generator. the generator converts this mechanical energy in to electrical energy.

There are several variables that determine the amount of energy produced: wind speed, diameter of the rotor, density of the air, and efficiency of the turbine.

A great product for teaching wind power concepts is the Basic Turbine. The Basic Turbine is a great start for teaching about wind energy in the classroom. Visit www.heathscientific.net to purchase this item. This is the most affordable and robust wind turbine kit on the market. Design blades and test your power output with a multimeter, LED bulbs, or an ultra capacitor.

The instructions that are included will show you how to build this PVC turbine, how to make blades for your wind turbine, how to use a multimeter to record electrical data and will discuss some basic wind energy science.

Solar Panels (Photovoltaic Cells)

Why are Photovoltaic Cells Black?

The dark color reduces the amount of photons reflected. Photons that are not absorbed by the panel cannot be used to produce electricity.

 

 

Solar Science Kit

Solar Science Kit

 

What are Photovoltaic Cells Made From?

Silicon is the major material in the cells. Pure silicon crystals are poor conductors of electricity. Other elements are added to the silicon, such as, phosphorus and boron. When the energy from the sun hits the cell, the electrons in the elements begin to move around. The sun causes the panel to have a positive and negative side. This electrical difference causes electrons to flow through a diode.

What Factors Affect the Production of a Solar Cell?

The factors that most affect the production of a solar cells are the angle of the panel in relation to the sun, the peak wattage, the light intensity and the hours of sun exposure.

How is Wattage (or Power) Calculated?

The formula for power is Power=Current X Voltage. Power is measured in watts, current in amperes and voltage in volts.

The Solar Science Kit has a small motor, photovoltaic cell and disc that works well in demonstrating this in a classroom or home setting.

Energy Conservation, Conversion, and Windmills

What is a Generator?

When a magnet moves toward a metal object, the electrons in the metal move. As a result, when a magnet moves near a copper wire, electrons in the copper move. Generators use this principle to convert mechanical energy (the rotation of a wire coil,or rotor around a magnet) into an electrical current (electrons flowing through the wire). A motor performs the opposite function by converting electrical energy into mechanical energy. For the most part, all generators work the same. The item that separates them is, “What turns the rotor?”

Windmill Generator Kit

Windmill Generator Kit

Energy Conversion in a Windmill

Obviously, in a windmill, the wind is rotating the wire coil around the magnet. This generator is taking the kinetic energy from the wind and converting it to electrical energy.

Windmills are rated based on output power (watts), working voltage (volts), start up windspeed (mph), survival wind speed (mph), rated rotation of the blades (rpm) and the diameter of the blades (also called the rotor). In general, the larger the rotor diameter the more wind that is intercepted and the more electricity produced. There are do-it-yourself plans available for building your own windmill. No waste or pollution is produced during this process.

When discussing this in the classroom or entertaining your children on the weekend, there are some small demonstration kits available. The Windmill Generator from 4M Kidz Labz TM is an excellent activity.