Problem 1: a small disk 5 mm in diameter is positioned and the center of an isothermal hemispherical enclosure aperture the disk is at 900 k, and has a diffuse gray surface with an emissivity of 0.7. the hemispherical adiabatic enclosure has a radius of r 100 mm and an emissivity 450 of 0.85. the enclosure has a small aperture of 2mm diameter. by radiative network analysis, determine the radiant power leaving the enclosure through the aperture outside the aperture the environment is at 300 k. (let the disk be surface 1, the hemispherical enclosure is surface 2, and the aperture be surface 3)

Ahot-air balloonist, rising vertically with a constant speed of 5.00 m/s releases a sandbag at the instant the balloon is 40.0 m above the ground. after it is released, the sandbag encounters no appreciable air drag. compute the velocity of the sandbag at 0.250 s after its release.

Which branches of natural science include the study of an organism that lived 10 million years ago

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?