Cooling curves Arcminutes of longitude Clouds summer 2021

January 31, 2022

Some imprudent bush whacking to retrieve banana leaves for laboratory four eventually led to tight lower back muscles that inveighed against doing swizzle frequency versus velocity for laboratory six. I returned to a cooling curve laboratory.

The session started with a review of the Celsius temperature scale and a demonstration of the remote surface temperature measuring device.

I began the laboratory portion with the open question of what happens to temperature over time for a cooling object? What mathematical model does cooling obey? Linear? Something else?

I then let the students discover the behavior.

Melissa

I had put on the board for the first column the time in minutes. I told the students to wait one minute before putting in the thermometer to prevent the melting thermometer problem. I noted that they would then need to wait one minute to take their first measurement at two minutes. Then they could take a measurement and three minutes, four minutes, five minutes. I meant one minute intervals. I obviously bungled this because every single group waited two minutes, then three minutes, then five minutes, then six minutes: they took the time values to be wait times, not clock times.

When one measures cooling temperatures using a monotonically increasing time interval, the temperature fall is less non-linear if one then plots these as equal intervals. Which the students were obtaining because their first column was numbered 0, 2, 3, 4, 5. So they were getting very straight cooling curve lines.

This effect can be seen using the data above:

When I saw these graphs appearing I was puzzled, but the students were quite content with a linear decay. This was repaired by restoring the duration since start, but that undoubtedly blunted the understanding of the laboratory.

The students used their phones to track time, resetting the timer each time to a one minute longer interval. A clock in the classroom would perhaps be a better choice, but the WiFi was up and down and thus the Chromecast clock was not usable.

The time correction can be seen in the third table on the right.

Blossom checks her GPS

Another GPS rolled over and died, the class is down to five GPS units. One student used an app on their phone.

Angelica checking her GPS

The WiFi behaved erratically complicating the usual arc of this laboratory. Rain also headed our way, and then veered off to the right. I explained that I sent the rain down to Pehleng.