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 Parallel Circuits to Your Students

circuit

To start, we need to define current and voltage:

  • Current is the rate (or speed) at which the electrons are flowing through the circuit and is measured in amperes (Amps).
  • Voltage is technically the electrical potential difference between the beginning and end of a circuit….or simply, the force at which the current travels through the circuit. Voltage is measured in Volts (joules/coulomb).

We are going to start with the simple circuit we created in a previous post (connect the alligator clip to negative side of battery, then connect to knife switch, knife switch to lamp holder, lamp holder to positive side of battery).

Now let’s make some modifications and create a parallel circuit. In a parallel circuit, the voltage stays constant in each branch of the circuit.

Creating a Parallel Circuit

Using our simple circuit with the knife switch in the upright position, we are going to add another load (light) and create a parallel circuit.

  1. Take a wire with alligator clips and attach to one side of the existing lamp holder.
  2. Using a separate wire, attach one end to the other side of the existing lamp holder (*note: there will be 2 clips attached to each side of the existing lamp holder).
  3. Take the ends of the two wires that are free and clip one to each side of a new lamp holder with light bulb. When the knife switch is closed, both lights illuminate.

In a parallel circuit, the voltage stays constant in each branch of the circuit. So, using a 1.5V battery, both bulbs are receiving 1.5V of electricity. This is the reason both light bulbs have the same brightness. If you measured the current, you will find that the current is divided into each branch. Therefore, if 10 amps of current were flowing through the circuit, each light (or branch of the parallel circuit) would be receiving 5 amps of electricity. Adding the amount of current in each branch together, will give the total amount of current introduced into the circuit.

Heath Scientific has a kit called “Making Circuits Simple.” This kit has all you need to complete this experiment.

Explanation of Color From a Prism

Although no one knows who invented the prism, Sir Isaac Newton was the one who discovered that the rainbows they produced were merely the components of white light that had been separated.

What is White Light?

Usually just called light or “visible light,” white light comes from the sun. It can also be produced by incandescent light bulbs, fires, or anything that gets hot enough to emit visible light.

How White Light becomes a Rainbow

When light shines through a prism it enters at an angle and exits at another angle. Different frequencies (color) of light are refracted at slightly different angles when they enter and exit the prism at an angle. Refraction is the change of direction that occurs when any type of wave goes into a different material at an angle.

Because the diffraction angle is different for different colors, the white light gets separated into different colors as it passes in and out of the prism.

What Colors come from a Prism

Although people can perceive around 10 million colors, prism colors are classified as one of the following seven:

  1.    Red
  2.    Orange
  3.    Yellow
  4.    Green
  5.    Blue
  6.    Indigo
  7.    Violet

How to get a Bigger Colors from a Prism

The further away the prism is from the target surface, the larger but also dimmer the colors will be. If you have a dark room and a bright sun, it will show up beautifully at a distant wall.

The closer to the prism the more brighter and bunched up the colors become. If you get too close to the prism then you will not be able to distinguish the colors anymore.

Color Lessons for Children

Catch the Rainbow.

Younger children love to chase the rainbow along the wall and around the room as you tilt the prism. They will try to catch the rainbow in their hands.

Share observations.

Children of all ages can make observations of the prism’s rainbow. Preschool children, like the 2- and 4-year-old pictured here can describe what they see. Ask if they hear, smell, or feel the rainbow.

For older children, ask if the colors are in separate bands or if they run together. Is each color equally wide, or are some wider than others?

Color what you see.

Have the prism shine onto a table or other solid surface, provide a variety of crayons and have them color what they see or color around it.

Test different light sources.

Try a strand of colored Christmas lights–what colors come out of the prism? What about that yellowish light in the lamp? Or a black light?

If using Sunlight

Keep in mind that the earth is rotating, so if you are using sunlight the color will move and you may have to readjust the prism for maximum color and shape.

Related Products

4″ Prism
Diffraction Gratings

Other Resources

What is White Light
Spectrum from Prism

How to activate and reuse Glacial Heat

Activation

Glacial Heat, commonly known as hot ice, is easy to use.
Bend or flex the metal disc in the Glacial Heat pack. Instantly, ice will form on the disc and spread through the pack. You will feel the pack get warm. It should stay warm for at least half an hour.

The pack remains frozen at room temperature until you prepare it for reuse.

Reuse

To reuse the pack, put it in boiling water for about 10 minutes. I recommend medium heat on your stovetop. You might smell a slight odor of plastic–that’s okay. Flip the pack in the water while heating to avoid melting the rubberized cover.

Take the Glacial Heat pack out of the water after all the crystals are gone and let it cool. Once it cools completely, it is ready for use.

Video instructions

The science

Curious about the science behind the Glacial Heat pack? Check out these links:

Teaching Electricity and Simple Circuits to Elementary Students

Circuits in the elementary classroom

Teaching circuits to students

Electricity can be a complex and imposing topic to present to your students. Before we talk about circuits, let’s go over a few definitions:

  • Load - A device that does work or performs a job (i.e., the light bulb in our circuit).
  • Electrical current - The flow of electrons from an area of high concentration (“a lot”) to an area of lower concentration. *Note: the negative side of the battery has a high concentration of electrons.
  • Electron - A negatively charged particle that orbits the nucleus of an atom.
  • Generator - A device that converts mechanical or chemical energy into electricity. Wind, water or an engine can power a generator.
  • Electrical circuit - An electrical path that is closed (all parts connected), allowing the electricity to return to the original source (the battery).
  • Parallel Circuit - A circuit in which the components are connected like a ladder. This circuit splits the voltage equally to all of the components.

Simple Circuit

Creating a Simple Circuit

  1. Place a “D” cell battery in a battery holder. The battery holder will allow you to attach wires with alligator clips to the positive and negative ends of the battery.
  2. Now, screw a small light bulb (mini lamp) into a lamp holder. Like the battery holder, the lamp holder will allow you to attach alligator clips to the light bulb (your load).
  3. To complete the circuit, you will need two wires with alligator clips. Use one wire to connect the negative side of the battery to the lamp holder. It does not matter which side of the lamp holder the wire is attached. Connect the positive side of the battery to the lamp holder using the second wire. This wire will attach to the opposite side of the lamp holder. The light bulb should be lit.

Remember, the voltage of the battery and light bulb should be similar. If the battery voltage is too much larger than the voltage capacity of your bulb, the bulb will burn out. A “D” cell battery provides 1.5V.

Simple Circuit with Switch

Adding a Knife Switch to a Simple Circuit

We will modify our simple circuit described above to complete this task.

  1. Disconnect the alligator clip that is attached to the negative side of the battery and re-connect it to one side of the knife switch. Make sure the knife switch is in the upright position.
  2. Take a separate wire and connect the negative side of the battery to the knife switch. Notice that the light is off.
  3. Lower the arm on the knife switch to connect the circuit and light the bulb.

The knife switch allows you to discuss breaking the circuit and stopping the flow of electrons.

Heath Scientific provides a kit called “Making Circuits Simple” that includes all of the components described in this article. It’s an easy, all-in-one kit to demonstrate circuits to your students.