Ball bearings of 20% nickel steel, 10 cm spherical diameter, at 200ºC are quenched in 20ºC oil where the convective heat transfer coefficient is 200 W/m^2K. Determine a) the time for the surface to reach 80ºC, and b) the thermal energy exchanged during this time.
What will be an ideal response?
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The Sun and the Moon have the same angular size. If the Sun is 400 times farther away from the Moon, the Sun must be ________ times the size of the Moon.
A. 400 B. 1/400 C. 4 D. 1/4 E. 4?
Marie & Pierre Curie
A) discovered radioactivity. B) proposed the plum-pudding model. C) proposed the tiny central nucleus idea. D) observed back-scattering from nuclei. E) discovered radium and polonium.
An ideal Polaroid will transmit 50% of nonpolarized incident light. How much light is transmitted by two ideal Polaroids oriented with their axes parallel to each other?
A) 0% B) 50% C) 100% D) between 0% and 50% E) between 50% and 100%
Newton's law of gravitation applies to all ______________
Fill in the blank(s) with correct word