Science Methods II Week 4 Blog Post

 1. The big question addressed in lab, and a description of what you did

        -     What affects how long it takes a swing to go back and forth?

        -     This week in lab we tested the question listed above. The variable my group tested was the length of the chain/string of a swing. The question we were attempting to answer was "How does the length of string affect how long it takes a swing to go back and forth?". Before we began our testing, our hypothesis was that if the string/chain of a swing is shorter then it is going to take a shorter time to go back and forth. To answer our question, we tested three different lengths of string. These were 60.5cm, 42.5cm, and 24.5cm. We tied a washer to the end of the string and pulled it back to a height of 29cm. From there we let go of the string and timed how long it took for the swing to go forward and back. The average times from the longer string to the shorter string were 1.82s, 1.56s, and 1.14s. From this data, we concluded that the length of the string/chain on a swing does have an affect on how long it takes the swing to go back and forth. Our hypothesis was correct, as we saw that the shorter the string was, the less time it took to go back and forth. 

 2. A description of what you learned in Thursday's lecture

        -     In lecture this week we continued our conversation on swings and what variables affect the time it takes for a swing to go back and forth. One of the first things we learned is that the term for the time it takes a swing to go back and forth is a period. We then went over Newton's first and second law. The first law explains that an object will keep the same speed and direction, unless an external force acts upon it. The second law is surrounded around the equation, Force = mass x acceleration, explaining that larger masses are harder to accelerate, which helps to explain the variable of weight and its affect on how long it takes a swing to go back and forth. During our testing, we found that weight does not have an affect on how long it takes a swing to go back and forth. Something with a larger mass receives a harder pull of gravity, and they also take a longer time to accelerate. In the end, weight does not have an effect on how fast it takes a swing to go back and forth because these two affects cancel each other out. One of the last things we talked about was energy and what kind of energy is seen in a swing going back and forth. We learned that there is gravitational energy when the swing is at the top, and the energy turns into kinetic as the swing goes towards the bottom. 

 3. Answer questions about the weekly textbook reading:

        -     What did you learn?

            -     Something I learned from this reading is how the pendulum clock came to be. The reading explained that Galileo observed that a pendulum took the same amount of time to swing back and forth as a swinging chandelier did. The scientist Christiaan Huygens then created the first pendulum clock using the observations Galileo had made. This became a very successful way to tell time as it was accurate between 15 seconds, while previous clocks were only accurate between 15 minutes. 

        -     What was most helpful?

            -     Something that was helpful in this reading was all of the connections they made between pendulums and other objects like swings, grandfather clocks, and wrecking balls. Swings and wrecking balls are something many people are familiar with and have an idea of what they do. Connecting something we know with something something we might not know a lot about (like a pendulum) helps us to gain a better understanding as we get to see what they have in common and how they work alike.

        -     What do you need more information on?

            -     Something I need more information on is what potential energy is. It explains in the reading that a pendulum has potential energy at first and then switches to kinetic energy as it goes down, however, I thought it started out with gravitational energy.

        -     What questions/concerns/comments do you have?

            -     Are gravitational energy and potential energy the same?