Ne of the problems of in-air testing of nuclear weapons (or, even worse, the use of such weapons! ) is the danger of radioactive fallout. one of the most problematic nuclides in such fallout is strontium-90 (90sr), which breaks down by β− decay with a half-life of 28 years. it is chemically similar to calcium and therefore can be incorporated into bones and teeth, where, due to its rather long half-life, it remains for years as an internal source of radiation. part a what is the daughter nucleus of the 90sr decay? what is the daughter nucleus of the decay? 9039y 8537rb 8436kr request answer part b what percent of the original level of 90sr is left after 56 years? nothing % % request answer part c how long would you have to wait for the original level to be reduced to 6.25{\rm %} of its original value?

If m_b=mzd= 43, find mzc so that quadrilateral abcd is a parallelogram o 86 137 o 129 43 description

I've been working on this for a few days and i just don't understand, it's due in a few hours. you. the direction of a vector is defined as the angle of the vector in relation to a horizontal line. as a standard, this angle is measured counterclockwise from the positive x-axis. the direction or angle of v in the diagram is α. part a: how can you use trigonometric ratios to calculate the direction α of a general vector v = < x, y> similar to the diagram? part b suppose that vector v lies in quadrant ii, quadrant iii, or quadrant iv. how can you use trigonometric ratios to calculate the direction (i.e., angle) of the vector in each of these quadrants with respect to the positive x-axis? the angle between the vector and the positive x-axis will be greater than 90 degrees in each case. part c now try a numerical problem. what is the direction of the vector w = < -1, 6 > ?

Find the volume of the solid bounded by the plane z=0 and the paraboloid z=1-x^2 –y^2