Find the expressions for the unit vectors in cylindrical coordinate system, p, φ,2. in terms of x, ý, 2. find the time-derivative of each. hints: unit vector p is defined in (x, y) plane. remember that α -φ is perpendicular to a the easiest way to find φ is to express rho through φ and add 90 degrees

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.

Earth's atmosphere is composed of mostly two gases. name the two gases that make up the majority of the atmosphere and use the pie chart to tell the percentages of each.

Radioisotopes often emit alpha particles, beta particles, or gamma rays. the distance they travel through matter increases in order from alpha to gamma. each radioisotope has a characteristic half-life, which is the time needed for half of a sample of radioisotope to undergo nuclear decay. which quality is desirable for a radioisotope that is used for medical imaging of a specific organ? check all that apply. half-life of several years half-life of several days half-life of several seconds emission of gamma rays emission of alpha particles ability to be attached to a compound used by the body ability to pass through the body without being absorbed