A teacher asks students to identify which demonstrations show physical changes and which show chemical changes. Which demonstration shows a physical change?
A. Baking soda is mixed with vinegar. The mixture bubbles.
B. A dish of water is placed in the freezer. The water turns solid.
Ο Ο Ο Ο
C. A piece of pH paper is dipped in clear ammonia. The paper turns from yellow to pink.
D. Hydrogen peroxide solution is dropped on a potato slice. The liquid bubbles and fizzes.

Aforce of 200 n is applied to an input piston of cross-sectional area 2 sq. cm pushing it downward 2.8 cm. how far does the output piston of cross-sectional area 12 sq. cm move upward? show all work.

What is the weight of a 8-kg substance in n, kn, kg·m/s2, kgf, lbm·ft/s2, and lbf?

Asquare 1m x 1m plate is shown below. all four of its edges are kept at 0 co. at t=0the temperature distribution is given by: y xtsins n75)=.a) using separation of variables determine the temperature distribution t(x,y,t)along the plate at any time t.b) discretize the heat conduction equation +=22222 txtusing a second-order centered difference scheme for the two second derivatives and a first-order forward euler scheme for the first derivative. using von neumann stability analysis, determine the stability criterion for the proposed discretization scheme in terms of , hand t. solve for the maximum allowable time step tmax