Wait... is that me? RUNNING?

Yeah, I know, a photo of me actually running may seem like a photo shop miracle, but I promise it actually happened.

This photo can be explained by one thing: MAGIC.

Alright, just kidding, but the reason my knees are bent can be explained by Rotational Inertia. Runners bend their knees when running because it lowers their center of gravity closer to the base of support making them harder to push down, and in a sport like Lacrosse some contact is  possible. Also, by bringing mass closer to the center of mass rotational inertia decreases meaning the ability to spin increases. And hey, you need to be able to make those quick turns!

Oh Hey Unit 5, Leaving So Soon?

This unit was FLIPPING CRAZY! We twisted and turned every which way into learning about Torque, Angular Momentum, Tangential and Rotational Velocity, Conservation of Angular Momentum, and even Centripetal and Centrifugal forces.

The end.



Just kidding! Like anything in physics, it takes a it more than a term to make it all sink in. This unit was intense in examples like flipping gymnasts, whipping roller derby girls, and even the occasional race car. It all began with tangential and rotational velocity. Rotational Velocity is the time it takes for 1 rotation, or the number of revolutions in a certain time period. Tangential Velocity is the distance converted in a certain amount of time. We applied these properties in class when we did an example outside.

We stood in a line and then were asked to turn, in attempting this we found out that the person at the axis only needed to take tiny steps, while the person farthest from the axis had to take huge steps. This is because the person in the middle has a lower tangential speed than the person farthest away meaning they have to move faster. Next we found our way to Rotational Inertia

Rotational inertia is how much an object is willing to spin. If the Rotational Inertia is higher the object will be harder to spin, while if the rotational inertia is lower and object will spin faster. Wan observe this when a figure skater skates into a turn, when she wants to spin she draws her arms in, decreasing her rotational inertia and increasing her speed. This occurs because she is pulling her mass towards the axis, or center of gravity in her body. 

And then we got into the more familiar stuff like conservation. No, not conservation of plants or endangered animals, but conservation of angular momentum. Conservation of angular momentum is the total angular momentum before= the total angular momentum after:
Angular momentum is affected by rotational inertia and rotational velocity.

BUM BUM BUM TORQUE
Torque~ what causes something to rotate. 
Torque=(force)(lever arm) 
lever arm = the distance from axis rotation. 

And finally, the real and the not real forces. 
Centripetal force- the force that draws things towards the center
Centrifugal force- NOT REAL (the name for a force that throws an object outward.)
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I wish I would have gone in in the mornings a bit more for this unit, but overall I kept up with my blog posts and homework and it helped with my overall understanding of the unit. That is my goal for the next unit. 

I think my passion for this class is really starting to come out as I've become more engaged in class and made a stronger effort to be a full part of group work. 

This unit was challenging because it involved many concepts that seem counter intuitive. Like the idea of Centrifugal force. But I really enjoyed it as it explained many athletic things I found interesting like diving and gymnastics. I think I'm really going to miss Unit 5.

Torque, Meter sticks, and Weights Oh My!

Bum bum bum bum bum iiiiiiiiiiiiiiiiiiiiiiiiiit's LAB TIME!

There comes a time in every unit when we have to band together, unite as brothers to complete an intense and life endangering mission.

Yeah okay, that may be taking it a bit far, but lab's are a huge part of every unit and, more often than not, they challenge us to be creative thinkers and problem solving individuals. This lab demonstrated the ideas we've learned thus far in regards to this nifty thing called Torque (looking back at my old blog posts I've realized I really like the word nifty).

Using only a meter stick, a 100g weight, and a calculator, we managed to find the mass of a meter stick.

To begin we had to get our facts straight, making a list of formulas:
Torque= lever arm x force
Force= mass x gravity

Then we stated some common facts, y'know, those things you think you know but always forget:
Torque will be the same on both ends of the stick because opposing torques must cancel one another out for an object to remain in balance.

The Center of mass will be in the center of the object.

Now the real fun can start.

Using these formulas we managed to calculate fairly accurately the mass of the meter stick.

The best part of this lab, for me, was having the chance to teach it to other students, it was so awesome to share what I had learned and I felt it really reinforced my knowledge.

Just Keep Spinning (Torque)

Oh hey awkward accent Judo man.

In this video the instructor uses Judo, a form of martial arts, to show torque. He goes on to explain how a certain technique creates a longer lever arm which allows for a greater movement quality.

He's pretty awesome too :)

I'm Flipping Out Over Here!

Flips! Turns! Spins! I CANNOT HANDLE THIS UNIT! I'm FLIPPING out over here!

Well, that may have been a bit dramatic, but haven't you ever wondered how those divers in the olympic manage to do those crazy twists and flips? Thanks to physics, I now have the answer. Prepare yourself.

HARD WORK!

Na, I'm just kidding, that's important, but it has nothing to do with physics.
These spins relate to something called Rotational Inertia, which is how much an object is willing to spin.
The magic in these flips is the positioning of the hands of the divers. When they are flipping they tuck their arms close to their body, bringing their mass closer to center, decreasing their rotational inertia and making them spin fast enough to complete the turns.