Vector Kinematics Reflection

To start the year off, we began learning about 2D vectors, relative velocity, and projectile motion. Coming from IB Physics SL 11, these topics were familiar to me, however, I found it beneficial to study these topics in greater detail, and spend more time on each topic.

When learning about 2D vectors, we learned methods of adding and subtracting.  We learned components method, which I had learned last year, but was difficult to remember. Components methods involved drawing each vector separately. Each vector has an x component and y component using trigonometry to find the values of each. Once we have the components, we can either add or subtract the x components of each vector and the y components of each vector and resolve them into 1 x component and 1 y component. With these vectors, we can add or subtract them, by solving the right triangle they create. The magnitude can be found using the pythagorean theorem, and the direction can be found using trigonometry (SOH CAH TOA).

Next we learned about relative velocity, and how all motion is relative to an observer. This made us look at what a velocity was relative to. For example, 2 cars are driving side-by-side at 50 km/h. A person is standing on the side of the road and watches them drive by. The person standing on the side of the road sees the cars pass at 50 km/h, however relative to each other, the people in the car would not see each other move because they are moving at the same speed. We used subscripts to represent each of the velocities relative to each other and used a vector sum to find the velocity of a moving object, relative to the ground.

Lastly, we learned about projectile motion in 1 and 2 dimensions. Projectile motion in 1 dimension was review from Physics 11, however projectile motion in 2 dimensions was a bit more difficult. At first we focussed on projectile being launched horizontally. We also watch a video on Myth Busters, about how an object shot from the height as an object is dropped hit the ground at the same time because they have the same gravitational force acting on them. When an object has horizontal velocity, there are 2 dimension to the motion of the object as there is vertical acceleration from gravity, however the horizontal velocity is constant. When solving projectile motion problems, we separate the horizontal and vertical motion, and use the formula, D = V_it + 1/2at². We can find information like time of flight, the range of an object, and how high an object was dropped from, amongst other information.

http://www.mrfizix.com/home/projectilemotion.htm

The biggest difficulty I had with this unit was thinking of 2D projectile motion as having a horizontal component, and a vertical component. I was used to only solving problems with an object falling or being thrown vertically. For me, it just took a lot of practice problems, and braingenie questions to get used to separating the horizontal and vertical motion then using the information I have to solve the question. Braingenie was actually quite helpful for this as the questions are a different style from the practice problems we get in class.