This is fun.

• No classes on June 30.
• The schedule of the Saturday review classes is already posted on the UPCAT page.
• CAT reminders are posted here.
• Schedule of long test and other various exams on Exams page.
• Class funds: BRING 100 pesos tomorrow.
• Announcement:

June 18:

First UB - Econ test (2nd year classrooms) - bring #2 pencil.

Second UB - Batch Congress (ASTB hall) - attendance is required, food is allowed

• Other requirements for the week are posted here.
• Physics HW:

Assume that a penguin father is a circular cylinder with top surface area a, height h, surface temperature T, and emissivity e:

a) Find an expression for the rate Pi at which an individual father would radiate energy to the environment from his top and his side surface were he alone with his egg.

ANS: Pi = (σ)(a + 2h√πa)(e)(T⁴)

If N identical fathers were well apart from one another, the total rate of energy loss via radiation would be N(Pi)

Suppose, instead, that they huddle closely to form a huddles cylinder with top surface area Na and height h.

b) Find an expression for the rate Ph at which energy is radiated by top surface and the side surface of huddled cylinder.

ANS: Ph = (σ)(Na + 2h√πNa)(e)(T⁴)

c) Assuming a=0.34m² and h=1.1m and using the expressions you obtained from Pi and Ph, graph the ratio Ph/(N)(Pi) versus N.