In a market system, the central problems regarding how much and what to produce are solved through the coordination of economic activities brought about by ________ signals.
The Pfizer Inc of the United States of America (USA) and its partner BioNTech of Germany completed the phase 3 trial of their COVID-19 vaccine candidate, BNT162b2 against SARS-CoV-2 with 95% effective success rate.
A ball, thrown vertically upward, rises to a height of 80 m and returns to its original position. The magnitude of its displacement after 7 s of motion will be ____. (take g = 10 m/s2)