See saw Mass of a Meter Stick

Step 1- We planned to use these equations:

• Counter clockwise torque= clockwise torque
• Torque= lever arm x Force
• W=mass x gravity

We took measurements on the meter stick used to balance the meter stick and the 10N weight being weighed. These measurement were of the lever arms and the center of balance. Upon further corrections, i found why my answer was off in mass, but i will explain that later. We also took into account the weight of the 10N mass.

Our idea was quickly thought out because the method that the rest of the class had used highly confused us. We had talked about lever arms for some time in class and we thought a see saw method would be the best way to make the topic of lever arms very clear. This is because we would see the center of balance and the lever arms at the same time and seeing the project as a whole would make things easier.

Step 2 and 3- Record measurements and various procedures. Failures and successes.
My group found a different way of solving this lab. We made a seesaw and had a meter stick as the balance bar of the seesaw. On one side we had the 10N weight and on the other we had the meter stick, lying perpendicular, split at the 5o mark. We balance them out and on the balance bar the middle was at 56 instead of 50 which was the center of balance. So from the side of the weight, from the 56 to the end was 56, which made the lever arm for the side 28 and from the side of the wieght to the 56 was 44 which made the lever arm 22. We knew the weight of the weight was 100g so we needed to convert it to newtons. We first converted 100g to 10N by using the W= M x G formula. After knowing our weight we did 10N x 9.8 to find the force of gravity. This gave up 98N. So right now we know the lever arm and force of gravity on one side (weight side), but we only know the lever arm of the meter stick side. So we used the formula counter clockwise torque= clockwise torque. SO t=t. In other words, 28 x 98N= 22 x F. We continued and got to 2744= 22 x F. We then divided by 22 to find the force of gravity for the meter stick side. This equation led us to the answer of 124.72727272. We divided the force of gravity by 9.8 to convert it back to mass. We again used the W=M X G formula to find the weight of the meter stick and came out with 127.2727272.
The mass of the meter stick was around 141. This meant we were below a 5% error.

Unit Blog

• In this unit I learned about....

a whole bunch of interesting information. I learned about centripetal and centrifugal force. This explained my childhood confusion on why I would always go left when we turned right and bump into the door. This is because of inertia. My body wanted to continue in the same path so it swayed to the right but the door stopped me. The door is the centripetal force. I also learned the centrifigual is not a force, but more of just the feeling that you are fleeing from the center of rotation. I also learned about rotational velocity and tangential velocity.

• What I have found difficult about what I have studied is.........

I found it very difficult to understand rotational inertia, rotational velocity, and tangential velocity. I could not name the difference between rotational velocity and tangential velocity. Also the concept of rotational inertia was just too confusing. I didnt understand how weight distribution affected speed.

• I overcame these difficulties by…….

studying on my own free time. I eventually understood everything that i was confused by. I started to understand that it was called tangential speed because the direction of motion of an object moving along a circular path was tangent to the circumference. I also learned that rotational velocity involved the number of rotations or revolutions per unit of time. I also understood the concept of rotational inertia. If mass was distributed towards the center of rotation the object would be more likely to rotate and the further the mass the less the object would rotate.

• My problem solving skills and effort 

have increased. I no longer allow myself to quit, instead i think of alternatives to make things work. For example, just the other day in class we did a lab on finding the mass of a meter stick. I was completely lost, but instead of quitting and giving up I instead used my head and thought of an easier way to do it. We ended up makin a seesaw and finding the mass that way. Using formulas such as; torque= lever arm x force, and counter clockwise rotation=clockwise rotation we were able to find that in fact the sides of the seesaw were equal and therefore the mass and the meter stick weighed the same.

• My goal(s) for the next unit is to ………………. by doing …………………

not settle. I feel like i am at a good spot for physics but i know that i can do better! I am actually starting to become mentally attached to physics and I would not want that to lack because im satisfied. I am going to continue to work hard so that I can increase my understanding of physics, which is probably the most interesting class I have. 

This section of physics was much easier to connect to actual life. Just this summer my families car got a flat tire. We had to use a special tool to take the nuts off the cars tire. The lever arm on the tool was probably a foot long, big tool. But this made it much easier to take the thick nuts off the heavy car. Also my childhood questions of why I go left when we turn right has been answered. It is simply because of inertia. Also learning that centripetal force is the reason why I didn't fly out the car was interesting, too.

Torque Blog Post

This video was produced by Briggs and Stratton lawn mowing company. This video gives plenty of real life examples of torque. When it comes to lawn mowing torque is a more direct measure of power. The video explains that torque is a measure of rotational power. In the video, there is a diagram that shows the formula; t= r x f, which means torque equals rotations times force. It explains that an engine with more torque will produce more rotational power to the blade. The higher the gross torque rating the easier the job will be completed.

Rotational Inertia Video Post

This is a great example of Rotional interia and Rotation velocity. When sam starts his flip his body is slow due to the spread of his legs and arms. The spread of his body means his Rotational inertia is large, therefore his rotational velocity must be slow. This is due to the conservation of rotational momentum. The rotational momentum before equals the rotational momentum after. When rotational inertia is high, rotational velocity is low. In the middle of the flip sam brings his legs closer to his body which brings the mass closer to the axis of rotation. This makes his rotational inertia smaller, which then increases his rotational velocity. As you will realize, his speed increases when this happens and this allows him to complete his flip.