
This was a weekend of scientific experiement and observation (as well as other forms of procrastination) for me. On Saturday morning as I searched for a sugary snack to eat while I tried to get some homework done before going shopping for prom dresses, I found a can of "all natural" 7UP in my fridge. When I poured it in my glass, I found that streams of bubbles were coming from the same points on the bottom no matter what I did to the glass (no, I didn't turn it upside down). I then hypothesized that there were small irregularities in those spots, as I remeber from Chem that bubbles form on irregular spots, at least when water boils. So I found a glass that my dad had dinked up the bottom by stirring liquid with a spoon and poured the other half of the can in, and found a noticable column of bubbles coming from the center with all the dinks. I have support!!!!! And this was before I really even got into my homework at all. But I know, that's Chem. Here's the simple but funny Physics encounter of the weekend. As my mom and I got home today (Sunday) and were unloading the car of our few purchases and other stuff, my mom brought up the cups of water we had been drinking. To make things easier, my mom stacked two of the cups one inside the other. She then forgot that there were two cups and took hold of the top of the top cup. Normally they would stay together because the static friction force on the two surfaces of the cups was enough to hold up the bottom cup. However, in this case, we did not drink all the water. Therefore, the weight (mg down) of the bottom cup plus the weight of the water was enough to overcome the maximum static friction force dictated by the coefficient of static friction of the cups, creating a net force pointing down. Thus, the cup slipped off, hitting the wood floor of our house with acceleration -9/8 m/s^2 (or g), not leaving a dink but resulting in a large puddle of water on our nice wood floor that had to be wiped up before it hurt the finish. The water splashed out of the cup, obeying the law of conservation of momentum, at least at first, giving the many water droplets large velocities in the same general direction to account for the large velocity and mass of the dropped cup. Thus with these large velocities, the puddle was large as well, for many dropplets flew far away. But no harm done, plus I got to explain to my mom the Physics involved. I felt smart. :-)