The Physics of Billiards

The other day I was playing billiards with my friends down at Hawaiian Brian’s for our kickoff event. And it hit me that the game is a matter of vectors and where you hit the ball. When hit square almost all of the force is transferred to the ball. Meaning that you can use the equation (m1+m2)a=F(of the cue ball). Because a force is applied to both balls when they collide and accelerate and decelerate. Static friction and normal force push back on the cue ball while the initial force acts on the 13 ball. And they stop either from the kinetic friction slowing both, or they fall into the pocket. This is fairly simple, yes, but when it’s not hit square the ball takes on the vector at the angle the two balls collide at, as well as the spin. To account for these factors is extremely hard, and it never seems to work too well when you try to go through with the plan. Usually I just try to hit the ball as hard as possible and get lucky when they go in.

Thanks for reading, Mark.

Elevators

I took this picture while riding the elevator at Ward Center the other day. While riding it down, my body seemed to feel lighter, yet the force my body exerted to the ground never changed. The normal force pushed back less because I was accelerating downwards. Then after accelerating I felt normal because my weight and normal force was equal as shown in the picture. The elevator is not accelerating in any direction, so the net force is zero. In that case W=N when acceleration=0. When I was going down my net fore was not zero it was positive in downward direction because, a = positive downward. So the equation would be W-N=m(downward acceleration). Because of these factors I felt lighter, normal, and heavier as I accelerated, maintained speed, and decelerated. In my picture I am maintaining speed and demonstrating what the free body diagram would look like in this case. Equal normal force and weight force, as I am not accelerating in any direction.

Thanks for reading, Mark.

My Attitude

Right now I think that physics will be a fun and interesting class, as long as I remember to do everything. I realize that this post is going to be after the due date, but better late than never. Some of the hard parts including the tests and homework are manageable. I have never really been good at running, so this 4 quarter marathon might be doozy. Allow me also to explain my picture. I’m using it as a metaphor for the year to come, as this picture was taken after we won our regional and went to the world robotics competition. Similarly my idea of physics is that we did well enough in chemistry to make it to physics, but we still have a huge battle in front of us. As I was in that picture, I am fairly optimistic about the future of the class yet I still have some anxiety. Most of it is from my brother’s success in the class and having to live up to him. Other than that I am approaching this class as I approach all others, with cautious optimism.

Thanks if you read this Mark.