We started this unit with a thought experiment. If something falls at the same time something is propelled horizontally from the same height, which will hit the ground first? Then we were shown video of a projectile (steel sphere) being shot across the screen and it was slowed down with a screen shot every two seconds, then someone put sticky notes at the location of the sphere and there was a nice parabolic path shown by the sticky notes. The horizontal distance between each sticky note was the same distance apart. When there is a projectile, only Earth pulls it down. In the horizontal direction, there is constant speed, and in the vertical direction, there is constant acceleration. These were concepts that we were familiar about because we had developed a model for them earlier. We have a conceptual framework now because we talked about forces before talking about projectile motion, which is opposite of most textbooks.
We did Unit 6: Worksheet #1 problems and then took turns facilitating whiteboard sessions about some of these problems. This was time well spent because we needed to learn how to facilitate these for when we return to our classrooms to lead them in modeling. In this worksheet, we utilized the algebraic formulas and/or graphs of the situation to look at the area under the curve when applicable.
We then were given a situation for everyone to whiteboard. An object was projected off a cliff at a height of 45 meters at an initial horizontal velocity of 40 m/s. We were to accurately draw a motion map to scale where each dot has a change in time of 1 second. It took three seconds for the object to reach the ground. We made a data table to determine the horizontal and vertical position of each point, and drew the velocity vectors in both the horizontal and vertical directions. The question was then asked "At what velocity (angle and magnitude) does the object hit the ground?" We came up with 50 m/s at 37 degrees below the horizontal. This was cool because I had never seen this done before.
We then had a challenge to perform as a lab group. We had to setup a ramp onto the track (the track was a straightaway) so that we could determine how far a steel sphere would hit the top of an upside down cup. We determined what the constant velocity of the steel sphere would be and used that along with the height to determine where to place the cup. When we did the challenge, it landed right on top of the cup. Even when repeated, it landed on the cup again and again. Really cool.
Another challenge was to launch a projectile at a certain angle to hit a cup on the floor.
We then looked at a reading out of the 5 practices book and discussed them. There were some really good insights there.
No comments:
Post a Comment