Unit One Overview

What have we learned?

Inertia

In this unit I learned about the inertia of objects, but in order to grasp a clearer understanding of what it is you have to know Newton’s first and second law of motion

1^st law: An object at rest tends to stay at rest unless acted upon by and outside force.

2^nd law: An object in motion tends to stay in motion unless acted upon by an outside force.

Basically here we see the two natural states an object can be in until acted upon by an outside force. Inertia is the property of a object, not to be mistaken with a force. Mass is even a measure of inertia, objects with more mass have more inertia, meaning that they require more force to change it’s state of motion. If you look farther down on my blog I have posted a video that represents inertia well, I even put a description.

Equilibrium and Newton’s

Another two related topics that we learned are the concepts of equilibrium and net force. Equilibrium occurs anytime the net force (total forces) on an object add up to zero newton’s, this can only be accomplished when an object is moving at a constant velocity, and when it is not moving. A force is a push or a pull, therefore the net force is how hard someone/something is pushing or pulling on an object. A force in measured in Newton (N). Since weight is a force, we can tell how many newton’s are acting upon an object that has mass.  

Speed and Velocity

The first step in understanding speed is that it is the measure of distance someone/something has traveled over an amount of time (distance over time). For example when Usain Bolt runs the 200-meter dash, he is covering the same amount of distance (meters) as every other runner but in less time (seconds). Speed can be measured in various units, as long as there is a distance being covered in some given time, but the most common measurement is meters per second. The concepts of speed and velocity are very similar for both of them are measured in meters per second, and show how much distance someone is covering in a given amount of time. The significant distinction between the two is that velocity requires a specific direction; moreover, when discussing velocity we use vectors to describe the magnitude of speed and direction of an object. One example that helped me distinguish between the two was a racecar moving at a constant speed on a racecar track. Here the car is changing direction every turn it makes, but with velocity you can’t change direction without changing it’s velocity; therefore, the car is only moving at a constant speed (not constant velocity). Another way to change velocity other than changing direction is by speeding up or slowing down.

Acceleration  

Another main topic that we covered in this unit was acceleration. Acceleration is the change in velocity over the time (a=∆V/t). The symbol “∆” means change; we also learned that in this unit. The units for acceleration is meters per second squared (m/s^2) this can also be read as meters per second, per second, for it is the amount of change in velocity per second. What made the concept of acceleration clearer for me was the example of a ball rolling down 3 different shaped ramps.

In ramp A the ball moves with increasing acceleration, for the rate of velocity is increasing every second. In ramp B the ball moves with constant acceleration, which means that the speed of the ball increases at a constant rate. In ramp C the ball moves with decreasing acceleration, and although the ball is increasing in speed it’s acceleration is decreasing because the ramp is less steep in the middle.  The acceleration is decreasing slowly as speed increases.

Common equations that are asked that relate to acceleration are:

• How fast is “it” traveling?

The key word here is “fast” because instantly we know that the question relates to velocity. The equation used to solve this question is: velocity equal to acceleration multiplied by time (v=at)

• How far did “it” go?

Here we know that the question is asking for a distance, and the equation we use to solve this is distance is equal to one half the acceleration multiplied by the time squared (d=1/2at^2)

What I found most difficult in this lesson was distinguishing speed and velocity, and how you can have constant speed but not constant velocity. What really helped me in understanding this was the podcast project that I did with my group (video is at the bottom of this post). After much discussion and filming about velocity and change in velocity I became somewhat an expert on the definition of velocity. My first approach to homework assignments is to get it done quickly but at the same time diligently. The workload this year has definitely been greater, so I don’t get to spend as much time as I would like processing my physics work. The lack of time I get outside of class to work on homework only makes me want to pay closer attention in class so that I take less time trying to understand the homework. This strategy has worked well so far, I find that doing my homework after class or after listening to one of my teachers podcasts that it is rather easy to work through problems. My self-confidence in physics grows everyday as we learn new topics, even when posting on this blog I realize that it organizes my thoughts about physics well. Another thing that aids to this confidence is group work, for when my group came together to work on a podcast we were able to discuss the topic accurately to one another and when one of us had a question the rest of the group was able to answer it. A technic that I found helpful with all of my homework and quiz problems is patience. Taking the time to thoroughly read the question and check your answers can only increase the likelihood of you getting the question right.      

            My goal for the next unit is to spend more time studying for quizzes. This unit I wasn’t able to spend as much time as I would of liked on studying for my physics quizzes, so hopefully I will be able to make this happen by coming into conference period and asking clarifying questions that I may have.

• Here is a podcast about velocity that my group made in class, hope you like it!