11 Masse volumique du polystyrène Le polystyrène est un matériau plastique
transparent dont on fait par exemple
certains gobelets. Si l'on y souffle
un gaz lors de sa fabrication, on
obtient du polystyrène expansé,
sous forme de boules blanches.
1. La boule de polystyrène expansé
de la photographie a un diamètre de
12 cm. Calculer son volume.
2. La masse de cette boule est de 14 g.
Calculer la masse volumique du polystyrène expansé.
3. Si l'on immerge totalement un gobelet en polystyrène
dans l'eau, il coule. Est-ce que, comme lui, cette boule
coulerait ? Justifier.

Which describes increasing the efficiency of energy resource

Ateacher gives students four liquids commonly found in the kitchen - vinegar, apple juice, dish detergent, and milk - and ph indicator strips, which measure acidity. the teacher asks the students to put the liquids in order from most acidic to most basic. what type of investigation could the students conduct to determine the correct order for the liquids?

Intro: a solid ball of radius rb has a uniform charge density ρ. part a: what is the magnitude of the electric field e(r) at a distance r> rb from the center of the ball? express your answer in terms of ρ, rb, r, and ϵ0. part b: what is the magnitude of the electric field e(r) at a distance r express your answer in terms of ρ, rb, r, and ϵ0. part c: let e(r) represent the electric field due to the charged ball throughout all of space. which of the following statements about the electric field are true? check all that apply. e(0) = 0 e(rb)=0 limr→∞e(r)=0 the maximum electric field occurs when r=0 the maximum electric field occurs when r=rb the maximum electric field occurs as r→∞.