AP Physics #3

We learned more about dynamics this week. We learned about friction force and so on. Running sure is full of dynamics because running also involves friction force (kind of obvious but). In order to run, i need friction. Otherwise it will be impossible to go uphill. What enables me to kick off the ground is friction. When I'm running, i never go past my shoes' max friction force. I know this because I never slip when I'm emitting force as i try to run. If my shoes had very little maximum friction force, i would not be able to put that much force to run.
Also, another example would be the tire of a car. While i was in my friend's car, i noticed that the car's tire's maximum friction force is insane. Insane because the car was parked on a steep hill (around 50-65 degrees compared to flat ground). Normally, objects would slide down the hill but since the tire's friction is great, the car stays where it was parked. I forget but i remembered that in the reading it said that the car's tire's friction coeffiecient was around .87 or something like that.

AP Physics journal: Dynamics

Just like what we discussed in lectures, i felt the difference in net force while i was going up and down using the elevator. Though i was too shy to explaining to others why we are feeling the difference in weight in the elevator, i went over the reason why in my head.
another example of physics-related thing i experienced this weekend was, again, during the XC race. Because i kick off the ground while going down the hill (in other words, jumping down the hill), i am in the air for a little while. Because i accelerate down due to gravity, while i was in the air, i felt very light (less weight). This is exactly like that elevator example. Because there is a downward acceleration, while im in the air i feel less weight. However, when i landed, i felt extra weight on me. It is because my downward acceleration suddenly went down to no acceleration (deceleration). So i wondered wouldnt going down the hill be a good workout too? i think so lol

First Physics Journal

Two weeks of physics class had passed and I have managed to survive this course so far. Although I faced many difficulties, I still enjoy learning physics. However, I must say Problem Set #2's last problem was hard...How do you find the range for the shortest range?! Anyways, I'm starting to catch on with this whole equations and all, so hopefully I do good on the next test (none of that stupid mistakes i made in the first one...like thinking that fat line in the middle of the graph was axis lol). I'm guessing that 3D movement is exactly like what we're doing right now except we have three independent equations...or maybe not, who knows lol.

When i was running a xc race on saturday, i was actually calclating the average velocity of the pace i was running in and i tried to find the final velocity and acceleration in order to achieve that increase in velocity. my first mile was 6 min and 26 seconds and the race was 2.6 miles. So in order to run faster than 19 min for 2.6 miles, i had to run 1.6 miles in 12min and 34 seconds. i was actually amazed i was thinking through these kind of things in the race. Unfortunately, i decelerated because i got a side pain right after my first mile so i finished the race poorly.