Which of the following is an observation and not an inference? a. a cup with steam coming from it will be hot to the touch. b.dark clouds in the sky will mean rain later in the afternoon. c.bubbles form when two chemicals are mixed together. d.a plastic bag moving along the ground is being pushed by the wind.

Abeverage can is made of 3004-h19 aluminum alloy (elastic modulus 69 gpa, tensile yield strength 285 mpa, density 2.72 g/cm^3). the dimensions on the can are approximated as a thin-walled cylinder with a height of 4.83 inches, diameter of 2.60 inches. empty the can has a mass of 14.2 g. determine: a. the wall thickness of the cylinder b. assuming a pinned-pinned condition what is the critical load? c. assuming a fixed-fixed condition what is the critical load?