going nowhere...

I thought this parked car was a good example of what we're learning right now. Gravity is pulling it down and normal force from the ground is pulling it up. Because of its weight (mass x gravity) and the equivalent normal force, the car is going nowhere vertically. There are also no forces pushing it in any other direction so because of this, its' net force is 0. This is the reason why it's still at rest. Newton's first law says that unless acted upon by a force, things that are at rest stay at rest and things that are in motion stay in motion. This car won't move/go anywhere until its net force changes from 0 to some other number. (Since I don't think anyone's going to try and push this car, starting the engine is probably the only way it's going to go anywhere!)

dents

i was looking at all of the dents on my neighbor's car when it hit me (not literally) that the cause of them had something to do with physics. There's a tree high above where he parks so the nuts fall down and leave the dents. I guess it's something similar to free fall because excluding the wind and air resistance, the nuts are being pulled down by gravity so their vertical velocity is negatively accelerating. It's the same concept as my cat falling off the lanai although I think air resistance has a bigger effect on the nuts because although they are pretty heavy, they aren't as heavy as a cat. The top of the tree is around the same height as my lanai so ignoring air resistance, the nuts probably fall at around -20.288 m/s as well (after using the kinematic equation again). Although if you do consider air resistance, they probably fall at a slower rate than that because they'd get more air resistance than my cat. There sure seems to be a lot of falling around here...

raining cats

I was thinking about what I could do for this journal when I remembered how one of my cats had jumped off the lanai awhile ago. He was trying to catch a bird and although he did get it, he also fell about 21 meters down. He fell straight down so if air resistance is ignored, his acceleration would be -9.8m/s^2. If he started with 0m/s vertical velocity, that would mean his final vertical velocity would be around -20.288m/s. (I found this out with the kinematic equation V^2=InitialV^2 +2ax.) He hit the bush, and considering the rate at which he fell, that was probably way better than him hitting the ground. (His displacement was -21m because he fell down to a lower position than where he started, his acceleration was -9.8m/s^2 because of gravity and the fact that he was speeding up in the negative direction, and his velocity was -20.288m/s because he was going in the negative direction.) He had a major run in with physics, but he survived!

so far...

http://www.mulimed.com/images/Worry.gif

So far this class seems manageable, but only time will tell...It does however seem to have better labs than biology or chemistry. The labs take some time to do, but they're fun. I'm interested to find out what all of the other labs will be about, but at the same time I'm still pretty worried about all the tests (like the one next week!). I'm also kind of worried about how difficult it will be to understand the concepts as the year goes by. I guess I'd have to say that I'm still a little apprehensive about the course....

darts

I was at a party this weekend and while me and my friends were playing darts I realized it had something to do with physics. It's the same concept I talked about last week, just applied to a different event. By throwing it, the dart gains velocity going from 0m/s to a velocity in a negative direction (left, according to the picture). This would also be considered acceleration because there is a change in velocity even though there isn't much of a change regarding direction. Because the distance between the board and the person is too close, the final velocity of the dart right when it hits the board is not 0m/s . However, it is positive acceleration because the dart's speed is slowing down over time and it is going in the negative direction.

Well, I just finished eating breakfast on the lanai and decided this picture would be a pretty good example of what we just learned in class. It's kind of small, but there's a car (which i'll call carA) trying to get onto the freeway in the top right corner. We learned in class that acceleration is the rate of change in velocity and/or direction. This change is going to be important for carA because while it doesn't have to change the general direction that it is going in, it does have to go at a faster velocity in order to reach the velocity of the other cars on the freeway. (if it maintained its velocity, it would be slower than the other cars and would probably wait forever before it could change lanes) If left is the negative direction and right is the positive direction, then carA would have negative acceleration because it's increasing its velocity in the negative direction. It would also have negative velocity because it's moving in the negative direction.