Uma Câmara escura de orifício com 15 cm de profundidade produz uma determinada imagem para um objeto situado a 10 m do orifício. Qual a profundidade de uma câmara escura que, colocada a 20 m do mesmo objeto e produz uma imagem igual ao dobro da anterior? a) ( ) 30 cm b) ( ) 7,5 m c) ( ) 7,5 cm d) ( ) 30 m e) ( ) 60 m

An object weighs 40n in air, weighs 20n when submerged in water and 30n when submerged in a liquid of unknown density. what is the density of the liquid?

Nitrogen (n2) undergoes an internally reversible process from 6 bar, 247°c during which pν1.2 = constant. the initial volume is 0.1 m3 and the work for the process is 121.14 kj. assuming ideal gas behavior, and neglecting kinetic and potential energy effects, determine heat transfer, in kj, and the entropy change, in kj/s. show the process on a t-s diagram.

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.