Here you will find example phenomena for the four NGSS disciplinary core ideas in the physical sciences.
PS1: Matter and Its Interactions
What caused the 1947 Explosions at Lake Lenore, Washington?
In 1947, after WWII, there was an excess of pure metallic sodium. The sodium was commonly being used to make synthetic rubber as a substitute for natural rubber supplies. There were 10 tons of this highly reactive solid sodium. The transportation of these sodium barrels were considered to be a high risk, so there were no carriers willing to transport them in order to sell. The solution was to dump these sodium barrels into a lake in Washington. They did not want to cause harm, so they chose Lake Lenore since it is an alkaline lake that contained no fish. Once the sodium was dumped in the lake, there were large explosions and the pH level drastically changed, making the lake much more basic due to the sodium hydroxide formed. The explanation of this disposal in 1947 can be explained through the properties of sodium and chemical reactions.
On May 6, 1937, the Hindenburg arrived hours behind schedule at the Lakehurst Naval Air Station in New Jersey due to inclement weather with wind, rain, and possible lightning. The landing of the Hindenburg with these types of conditions was against regulations, but by the time the Hindenburg began its landing the weather was clearing up. The Hindenburg seems to have been traveling at a fairly fast speed for its landing and for some reason, the Captain attempted a high landing from a height of about 200 feet. Soon after the mooring lines were set, some eyewitnesses reported a blue glow on top of the Hindenburg followed by a flame towards the tail section of the craft. The flame was almost simultaneously succeeded by an explosion that quickly engulfed the craft causing it to crash into the ground killing 36 people. Spectators watched in horror as passengers and crew were burned alive or jumped to their deaths. As Herb Morrison announced for the radio, "It's burst into flames.... Get out of the way, please, oh my, this is terrible...Oh, the humanity and all the passengers.” In 37 seconds the great Hindenburg had completely burned. Of the 91 people on board, 36 had died.
What caused the Hindenburg to explode in 1937?
At first, chemicals used during rocket liftoff are in a less-reactive (stable) state, as can be seen in gases flowing out without any noticeable reaction. These chemicals (the fuel), like all matter, inherently have energy related to forces of protons and electrons of neighboring atoms. The bond energy between atoms is one type of energy. In some cases, matter can change without any added energy other than that taken from the surrounding environment—for example, the chemical reaction of baking soda with vinegar. In other cases, additional energy is required to destabilize the reactants and allow them to change. Just before rocket liftoff, sparks are applied to the fuel to provide this energy (the “activation” energy).
In a reaction that releases energy, the difference between the energy of the products (H2O) and the energy of the reactants (H2 and O2) results in excess energy being released into the environment [exothermic reaction]. At the particle level, it takes less energy to break the bonds in H2 and O2 molecules than that released when the new bonds in H2O molecules form. This energy is released into the environment as heat, light, and sound. Once the reaction starts, the sparks can be removed because some of the released energy causes more hydrogen and oxygen atoms to rearrange into water (similarly, once a fire starts, you don’t have to continue adding outside energy [heat] to keep the flame going).
To make the rocket launch, the chemical reaction takes place in a reaction chamber outside the fuel tank, where the gases are released at a controlled rate (not too fast or too slow). The released energy in this exothermic combustion reaction causes the gases to move faster, raising pressure, which causes the primary product (H2O vapor) to expand and exit from the downward-facing nozzle. The gas flowing out of the nozzle has mass and its downward movement creates a force (Newton’s Second law, F=ma). When something moves in one direction, there is an opposing force in the opposite direction (Newton’s third law). This creates the force that pushes the rocket upward and into space.
An empty tanker car was steam-cleaned, sealed, and left overnight. Overnight, the outside temperature decreased. At a certain point, the massive, sturdy tanker car imploded in on itself in an instant. What forces could have caused the tanker car to implode? How can changes at the molecular level lead to such incredible forces on the scale of a railroad tanker car?
Why did the tanker car implode?
To learn more about the threats of nuclear testing to human health, during the 1950's the Committee for Nuclear Information conducted a baby tooth survey. This survey emerged out of concern that nuclear testing in the atmosphere, as part of nuclear weapons development, could cause long-term health risks. As part of the survey, parents were asked to mail in their children's baby teeth for testing. As a result of a study of more than 30,000 baby teeth, mostly from children from St. Louis, Missouri, it was determined that a spike in radioactive Strontium-90, a chemical element that resembles the important nutritional element Calcium, was found in the teeth examined in the study. This was concerning because Strontium-90 was released in the atmosphere as a bi-product of the nuclear testing and was incorporated along with (and in place of) Calcium into the bones and teeth of developing unborn babies and continued even after birth. Because Strontium-90 has a half-life of 28 years, it was believed that these nuclear tests had unnecessarily resulted in what amounted to unnecessary and potentially harmful (e.g., potentially cancer causing) exposure to radioactivity over the life of these children.
PS2: Motion and Stability: Forces and Interactions
Voyager 2, was launched by NASA in the summer of 1977 from Cape Canaveral, Florida. It, along with Voyager 1, were to conduct closeup studies of Jupiter and Saturn, Saturn's rings, and the larger moons of the two planets. However, because of a once in a 175 year alignment of the planets, Voyager 2 was able to "swing from one planet to the next without need for an onboard propulsion system", to not only visit Jupiter and Saturn as originally planed when launched, but to also visit Uranus and Neptune. This spacecraft's flight path bent and increased its velocity enough to reach each subsequent planet using a "gravity assist" technique. Voyager 2 is the only spacecraft to have visited Uranus and Neptune. On Aug. 25, 2012 (35 years after leaving Cape Canaveral), Voyager 1 left our Solar System and entered interstellar space. Voyager 2 will soon join Voyager 1 as the first human made objects to enter interstellar space.
How was it possible for the Voyager 2 to visit so many planets on its path to interstellar space?
How can cell phones be charged wirelessly?
A wireless charger first needs to have an AC current moving though a coil of wire. This current will create a changing magnetic field and then this changing magnetic field will produce a voltage in another coil of wire that is near it. The amount of voltage that is created is based on the number of turns of the coil and the strength of the magnetic field.
One of the most familiar images of Yosemite National Park is Half Dome, the park’s tallest granite peak at nearly 5,000 feet. While thousands may have made the trek with nothing but sore leg muscles to show for it, clear warnings are posted that a climb here could be deadly, because Half Dome is a gigantic natural lightning rod. On July 27th, 1985, five men set out to climb Half Dome. When a storm hit, they sought shelter. The summit took a direct hit. Millions of volts of electricity arced over the wet stone surface—into the rock enclosure. The lightning strike killed two of the hikers and two others suffered massive internal injuries along with third degree burns. The fifth hiker was in motion when the lightning struck. Because little of his body was in contact with the rock, he did not ground the lightning’s electrical charge, and he escaped with minor injuries.
Why did the hikers get electrocuted climbing Half Dome?
Why do cookies bake in a car during the hot Phoenix summer?
Temperatures can reach up to 122°F in Phoenix, Arizona, during the summer months. The interiors of parked cars left out in the heat can reach temperatures that are far higher. In fact, if you place a baking tray full of cookie dough on the car's dashboard, they will cook! This occurs because of several different ways heat can transfer and be trapped.
PS4: Waves and Their Applications in Technologies for Information Transfer
Sound waves are initially created by some sort of vibration. Based on the basic properties of waves, (frequency, amplitude, wavelength, velocity, etc.) we know that the creation of sound waves has certain implications about energy. Being a mechanical wave, sound waves behave predictably when colliding with other waves. When a sound wave is created, it moves with a velocity that depends on the medium through which it is traveling and the general temperature. This causes an inherent kinetic energy. This energy is transferred to the particles in the glass when the wave comes into contact with them. When particles inside of materials have kinetic energy, they gain vibrational motion. This vibrational motion is enough to crack and eventually break the glass once the incoming waves have enough energy and are large enough (amplitude). In addition, the frequency of the incoming waves should be the same as the natural resonant frequency of the glass. If the particles vibrate at their resonant frequency, they will have more energy as a result. Breaking a glass with one's voice is not an easy feat to accomplish, but it is possible. In order to do it, the singer must find the resonant frequency of the glass. This can be done by tapping the glass with a fork, or wetting a finger and running it along the rim of the glass. Once this frequency is known, the problem becomes singing the note with enough volume. So, if the singer uses the correct frequency (pitch) and volume, then the sound waves produced will carry enough energy to crack the glass.
Why is it possible to break glass with only one’s voice?
How can a buoy be used to save whales from lethal boat strikes?
Boats or Vessels pose a significant threat to whales. If a whale is struck by a vessel going over 10 knots, it will like lead to a lethal encounter for the whale. For those whales, like the right whale that is critically endangered, these lethal encounters with individual whales have even bigger consequences. To address this issue, researchers have developed buoys that can detect whale calls. These detected whale calls are mapped to whale calls on record, specifically those of more endangered species of whales. When detected an alert can be sent to vessels within the vicinity of the detected whale(s), where the vessel can be slowed to avert these lethal encounters.