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!

Steps to a Successful Science Fair Project

Science fair project

8 steps to a successful science fair project. Photo by terren.

  • Did the student learn something from the project?
  • Did the student follow the scientific method to complete the experiment?

If the answer to each these questions is yes, then the student was successful. Let me give you 8 steps to a Successful Science Fair Project.

  1. The first and most important step is the Selection of a Topic. The topic should be of interest to the student and selected prior to designing the science fair project. Example topics could include oceanography, basketball, ballet, sharks, micro-organisms, magnets, etc.
  2. The second step involves some creativity. At this point, you must ask a question about your topic that can be answered in an experiment. For example, if the topic was micro-organisms, the question might be, “What surface in my house contains the most bacteria?”
  3. Next, you must research the topic and discover background information that will be useful for your experiment. In order to answer the question above, you would need to know how to grow bacteria, how to take samples, optimum growth temperature, safety procedures, where do bacteria grow, etc.
  4. Then, you need to take the question from step 2 and reword it, so that, a purpose statement is created. From the question we created in step 2, our purpose statement could be, “The purpose of my experiment is to determine which surface in my home contains the most bacteria.”
  5. Now take the purpose of your experiment and develop a hypothesis. The hypothesis is an educated guess as to the outcome of your experiment. Your hypothesis could be, “My hypothesis is that the toilet seat has the most bacteria.” Don’t ever change your hypothesis. Your hypothesis is based on your research and knowledge. If the experiment disproves your hypothesis, that is OK. An incorrect hypothesis does not make an unsuccessful project.
  6. Design the experiment. This is where most people start. Never start with the experiment, because many times the outcome is know. Learning and using the scientific method is the most important part. During this step, you will determine the materials needed, explain the procedure, collect data and record results.
  7. Draw a conclusion. The conclusion is simply, “Was my hypothesis correct or incorrect?” Your conclusion might be, “In conclusion, my hypothesis was incorrect, the kitchen sink was actually the area that contained the most bacteria.”
  8. The final step is to make an attractive science fair display. You should have label headings, such as, Purpose, Hypothesis, Materials, Procedure, Data/Results, Conclusion. Display part of your experiment. If parts of the experiment are not able to be displayed, use photos that explain your procedure and results.

The Effects of Temperature on Water Absorption in Warblettes

In this experiment, we are going to determine the effect of temperature on water absorption in warblettes.

To complete this experiment, you will need the following:

Procedure

1. Create an ice bath by placing a mixture of water and ice in the 500 ml beaker. Fill approximately 1/2 full.

2. Using a graduated cylinder, pour 50 ml of water into one of the 250 ml beakers. Place the beaker in the ice bath. This will keep the water cold during the experiment. For the purpose of this experiment, it will not be necessary to measure the actual temperature of the water. Our main goal is to compare cold and warm temperatures in general. The water will drop to between 5 and 10 degrees celsius.

3. Using a 50 ml cylinder, add 50 ml of hot tap water to the second 250 ml beaker. The water temperature will be approximately 40 degrees C and will continually cool during the experiment.

4. Add 40 Warblettes to each of the 250 ml beakers. Allow the Warblettes to absorb water for 20 minutes.

5. Take one beaker and pour the remaining water into the graduated cylinder. Measure this amount and subtract from the original 50 ml. This calculation will give you the amount of water absorbed by the Warblettes. Repeat this step for the second beaker.

Result

The warmer temperature water will promote faster growth of the polymer. Compare this to real life applications like:

  • Coffee, tea, sugar, and other solids dissolve faster in hot water.
  • Most bacteria grow best at warmer temperatures (close to human body temperature).
  • Ice on a contusion reduces bruising by slowing blood flow.

Warblettes can be used in many experiments and create interest and excitement while reinforcing scientific principles.

 

Teaching Chemical Changes in the Elementary Classroom

Sodium Bicarbonate, Calcium Chloride and Phenol Red

Let’s go over the procedure first and then we will discuss what is happening.

1. In a quart baggie, place sodium bicarbonate(1 tsp) in one corner and calcium chloride(1 tsp) in the other.
2. Lay the bag on its side and place a small cup (medicine cup size – 1 oz) of phenol red in center of the bag. Be careful not allow the any on the chemicals to mix yet. Seal the bag
3. Gently pour the phenol red where it spills into each corner. Do not mix the two corners yet.
4. Have the students feel each corner and make observations. Continue the observations for a few minutes.
5. Pick the bag up and gently move the bage side to side, mixing the chemicals. What happens?

Explanation

The side of the bag with calcium chloride becomes warm. The calcium chloride dissolves forming calcium and chloride ions. The release of heat (exothermic) is a result of the calcium chloride dissolving and not a chemical reaction.

When the sodium bicarbonate dissolves to form sodium, hydrogen and carbonate. It becomes cool (endothermic). The baking soda absorbs heat in order to dissolve. This is not a chemical change.

When the two sides are mixed, calcium carbonate is formed which is insoluble. Also formed are water and carbon dioxide. The carbon dioxide (gas) causes the bag to inflate. When the carbon dioxide dissolves in the liquid, carbonic acid is formed. This change in pH causes the phenol red to turn yellow. A chemical change has now occurred.

Remember to have the students use all lab safety measures. If the bag becomes over inflated, release some of the gas.

Hydrolysis – The Splitting of Water

See the Oxygen molecules bubble and the indicator turn pink

See the Oxygen molecules bubble and the indicator turn pink

Hydrolysis Water Splitting

Using a 9V battery, 2 electrodes and small gauge wire, you can split water into its component parts. This process is called hydrolysis. We add a small amount of salt to increase the conductivity of the water and an acid/base indicator to visualize the reaction.

The chemical formula of water is H2O. When the electrical current, produced by the battery, passes through the water, the water will split and the two electrodes will bubble. Hydrogen will appear at the cathode and the oxygen at the anode. The acid base indicator around the cathode will turn blue (because the free OH molecules raise the pH) and the area around the anode will turn pink (because the free hydrogen molecules lower the pH).

Looking at the formula for water, there are twice as many hydrogen atoms as oxygen. When hydrolysis occurs, twice as many hydrogen bubbles will be released as oxygen. You can visually see extra bubbles at the point where hydrogen is being released.

Hydrolysis experiments can be quantitative (how much hydrogen and oxygen are released?) or qualitative (can I visually see the reaction taking place?)