Displacement, Distance, Vectors

Displacement vs. Distance

The difference between displacement and distance is that displacement is the final distance between the starting point and the end point of an object. That is to say displacement is distance, but distance is not displacement. One can think of it as driving 20 km around the city and ending your journey 20 meters away from where you started. The total distance traveled was 20 km, but the displacement is 20 m. This is what I believe to be true.

Vectors

I've learned today that vectors are really important. Our class had an activity in which we looked at a set of pictures and determined if an object is accelerating or decelerating. One picture simply had a bunch of dots in a straight line with some dots closer to one another on the right end than the left end. Some chose the "decelerating" option while others, myself included, chose the "not enough information" option. The right answer was the "not enough information" option because the object could be going from right to left therefore accelerating or it could be going left to right therefore decelerating. There was no arrow to indicate the direction of the object.

Physics? Reality?

"What is Physics?" This was a question posed by our professor recently during a class discussion in which we expressed our opinions as to the definition of Physics. Some answered that Physics is the study of matter and energy while others said that Physics is the study of motion in the universe. Our group's answer was that Physics is the scientific study of the physical universe and the natural laws it obeys such as the forces of attraction, etc..

"What is reality?" This was another question we answered during the discussion. Our answer was that reality is what a person believes to be true through his/her observations. I had this idea that if a child was placed in a white room, assuming that the child never goes hungry or thirsty, then by the time the child reaches adulthood, the white room is his/her universe and reality. If a stone suddenly appears in the room, then his/her reality will shift to include the possibility that there is something more to the room. Our answer was more philosophical in nature than the other group's answers. Some argued that Physics and reality are the same while others argued that reality is just the perception of a person.

Physics may be defined in a Merriam-Webster's dictionary, but the true definition and nature of reality may not be known or understood for a long time. Nevertheless, the debate on what is reality and "real" will still continue.

Physics 4A lab 1

I met some new students and group mates Scott and Tony. We had our first lab exercise which was to give directions to one of our cars and to read another person's directions to his/her car. We managed to follow the directions quite well up to the point where we had to find the car. We took pictures of three possible cars because the original writer didn't describe the car. :/