Archive for March, 2009
Anyway, there are times when faux forces are awesome. Just to be clear, a faux force is needed to use normal newtonian mechanics when the reference frame is accelerating. To show this, let me look at the following problem. I will solve it without and then with fake forces.
Now, what about Ruff? What did he do this time to get me fired up? The episode was about something to do with hockey. Some of the kids were trying to make goalie padding – maybe? It started off fine. They had someone talking about what the gear does. 1) allows the interaction from the hockey puck to act over a larger area and 2) increase the time of the interaction. The time is increased by putting some squishy stuff in there. Good
Dan Meyer made this awesome photo. He posted it so that others could look at it and come up with lesson ideas to use with this. There are some very good suggestions in his comments. I wasn’t going to analyze this because I didn’t want to rob some students of the opportunity, but I can’t resist.
Suppose you put take two identical cans of soda out of the fridge and place them on the floor in the middle of a room. One can you leave alone and one can you cover with a wool blanket. After an hour, you come back and check on the two cans of soda. Which will be warmer?
I have always wanted to ask a question like this – but never found the right test for it. Perfect for a blog.
Question:
Suppose you are in your car at a stop light behind a truck. The truck is pulling a trailer with a rollable tractor on it.
When the light turns green, the truck [...]
So, I was in the student computer lab helping a student with a numerical calculation. I couldn’t help notice the student next to me was registering for classes. Here is here strategy:
Look at required courses. Check available classes. Check ratemyprofessor.com. Re-check available classes. [...]
I just got back from judging elementary level science fair (this is like kids in 6th grade or something). Here are some quick notes in no particular order.
The most recent problem I noticed (I don’t usually watch the shows, so I have no idea how many errors there are) was in the episode where some kids were trying to design a roller coaster. The kids wanted to make the car do a loop. At first, they did not start off the car at a high enough position and it didn’t make it through. The next time it started higher and DID make it around the loop. Your comment was something along the lines of: “Gravity gave it energy and inertia kept it going through the loop”
Well, the problem (as I discussed previously) is that small cameras are not stable and make “shaky” videos. Well, then increase the mass of the camera – simple. I wanted to test this idea and make a test video with and without extra mass on the camera. I was thinking – what could I attach to it? A 2 lb or 5 lb scuba weight came to my mind. Then it hit me: a water bottle.
One of the simple ways of determining the uncertainty of a calculated quantity is to use the uncertainty of the measured variables and find the max and min that calculated quantity can be. The example I used was in calculating the uncertainty for the area of a rectangle. So, the maximum and min areas would be: