## EMG- Chewing Lab

**I. Title:** Electromyogram Chewing Lab

**II. Purpose:** To associate the amount of electrical activity with the strength of muscle contraction, and to compare the masseter muscle function during different types of chewing activity.

**III. Hypothesis:** If different types of foods are chewed, then the foods that are harder with cause the electromyogram of the masseter muscle to increase because the masseter has to work more in order to chew harder foods.

**IV. Materials:**

- Foods: Chips, Pudding, Soda ( with s straw), Cookie, Banana, Peanut Butter, Ice Cream, Beef Jerky, Carrots, Celery
- Computer
- Vernier Computer Interface
- Logger Pro
- Vernier EKG Sensor
- Electrode Tabs

**V. Procedure:**

- Set up the computer and connect all the Vernier equipment.
- Prepare all food.
- Place electrode tabs on the upper check, lower jaw, and the arm.
- Attach the red and green leads to the tabs on the face, and the black one to the tab on the arm.
- Relax the jaw for five seconds while recording the EKG.*
- Clench the jaw for five seconds while recording the EKG.
- Repeat step five, but after the five seconds chew the different foods while continuing to record the EKG.
- After all foods are recorded, analyze the data to find the Δ mV for each food, and compare among all foods.

* It will be easiest if you save every recording under a different file. This will allow you to have a separate file for each food chewed.

**VI. Data: **Graph shows Δ mV for each food and clenching of the jaw.

**VII. Conclusion:**

After analyzing the data, my hypothesis proved to be correct. Harder foods resulted in a greater Δ mV in the masseter muscle than softer foods. Therefore, I can conclude that there is greater amounts of electricity in the contraction of the muscle when chewing harder food because more work is required.

This lab enhanced my knowledge about the masseter muscle, and why exactly there is higher amounts of electrical activity when chewing harder foods. I learned that the masseter is one of four muscles that produce chewing movements and that it is a thick, flattened muscle that can be felt in front of the ear when clenching ones teeth. I also learned that the amount of electrical activity in a muscle directly correlates with the strength of the muscle contraction. Therefore, I was able to conclude that in order to chew harder foods the masseter had to contract harder, which results in increases in electrical activity.

**NOTE: **Although I didn’t follow this experiment exactly, you may look at the

“true” experiment document by clicking Introduction to EMG Lab.

## New discovery in healing process of bones!

Today I stumbled across a very interesting article on ExtremeTech.com. This article I found, is talking about a very new and promising little bit of technology that a team from Washingtion State University discovered for healing bones. What they discovered was that it would be possible to print out new bone frames with a 3D printer.

In order to do this the team has modified a 3D printer that was provided by ProMetal to create bone bridges that could be implanted into a person and act as frame for new bones to grow on. The bridges are constructed out of fine ceramic powder that is coated on one layer at a time. They are also able to construct different implant styles for different people via a CAD program. Already, they have tested these in rats and rabbits, and have had promising results in the growth of bones. It is expected that human trials could start in as little as ten years.

This is very exciting news. If this was to work it would essentially eliminate the need for artificial replacements. Instead, doctors would be able to foster the growth of new bones. The best part of creating these bone bridges is that they actually dissolve after a period of time. So they will not be in your body for the rest of your life like artificial replacements are.

If you would like to take a look at this article you can click here.

## Bone Fractures

Here is the link to a Prezi I made that goes over the numerous types of fractures and explains the four step healing process.

## Wind Tunnel

The past two weeks in physics has been filled with work (with a good portion being productive work). Steven Sandoval and I decided that we were going to build a wind tunnel that we found online on Nasa.gov. You can see the instructions for this wind tunnel by clicking here. So far we have gotten pretty far on the project, we are currently on step 11 and I must say it is coming together nicely. Besides working on the wind tunnel we took a couple of days to play around with batteries and circuits. But in the end working with the batteries was a good idea because it gave us a way to power the d/c fan we need for the wind tunnel! Hopefully we will have the wind tunnel completed soon and will be able to collect some data on how an object’s shape can change airflow.

## Skin!

This is my popplet about skin and its major parts. Feel free to scroll around it!

## Trigonometry and Potatoes!

This is a post to go into further depth of the launch Steven, Brandon, Dustin, and I did with the potato accelerator. The data that we collected from one of the three trials showed that the total distance of the launch was 535 ft, the total time it took the potato to hit the ground from the initial launch was 7.13 seconds, the angle of elevation was 40 degrees, and the observed height was 5′ 6″.

In order to find the peak of the potato in the launch we used two different methods. The first method was with the h=½(g)t² equation. So first we divided the total time by two in order to get how long it took from the peak of the launch to impact (3.565 sec.). We then plugged that number into the equation along with the acceleration due to gravity (9.81 m/s²) and were able to approximate that the height of the peak was 62.339 m. or 204.524 ft.

After we found the height of the peak by using that equation we decided to find the height with trigonometry. In order to do this we had to find the distance from launch to peak and the angle of elevation from the observer’s eye (Steven). To find the distance from launch to peak we just divided the total distance by two and came up with 267.5 ft. Our observed angle of elevation came out to be 40 degrees in this trial. Now that we had all our data we were able to figure out that we would have to use tangent to find the height. So since we knew the angle of elevation and the distance from launch to peak, we were able to determine that our equation would be tan(40)=x/267.5. To solve for x we transposed 267.5 over and got x=tan(40)267.5, we then realized that we had to add in Steven’s height (only up to his eye) so our official equation was x=tan(40)267.5+5.5. We then solved for x and our height of the peak came out to be 229.959 ft.

Now that we had found the height of the peak using two different methods we were able to compare the numbers. From the first method we got 204.524 ft. for the height and from the second method we got 229.959 ft. for the height. So in conclusion the theoretical equation h=½(g)t² turned out to be reliable in finding the height of the peak of the potato in the launch.

## More physics…

Once again I am behind on blogging about what I have been doing in my physics class for the past couple of weeks so I thought I would try and quickly talk about what happened. For the past two week I have been working on the same project. To start off, Steven and I both researched how to determine the height of an object dropped if you only know the time it took to reach the ground and gravitational acceleration. We found a helpful equation ½(g)t² which allowed us to do exactly this. We wanted to find the height of a potato being launched from the potato accelerator so we got some data from our potato accelerator friends and were able to use it for the equation. They gave us the total time it took for a potato to hit the ground from launch (4.34 sec.) so we just divided that number by two in order to get the time it took from the peak of the launch to impact (2.17 sec.). We then took that number and pluged it into the equation with the acceleation due to gravity (9.81 m/s²) and were able to come up with 23.097 meters for the height of the potato. After we did all this good stuff we decided to try to theoretically calculate the height of the peak of the launch by trigonometry. In order to do this we created an inclinometer by attaching an eyepiece (cardboard tube) to a protractor and attaching a string with a bolt tied to it so we could measure the angle. The main purpose of the inclinometer was to allow us to measure the angle of elevation from Steven’s eye to the peak of the potato in the launch. After we completed the creation of our inclinometer we set off outside and were able to record distance, total time, and initial angle of launch from three trials. This current week we used trigonometry to find the height of the peak and also used the ½(g)t² equation to find the same thing and compared the numbers. I will report this data in another post soon.