The material that formed the earth was created in a supernova explosion approximately 6 billion years ago. The two most common isotopes of uranium, 238U and 235U were created in roughly equal amounts. Today, the earth contains more than 100 times as much 238U as 235U. Which isotope has a longer half-life? a. 235U has a longer half-life because more of it have decayed.
b. 235U has a longer half-life because less of it have decayed.
c. 238U has a longer half-life because less of it have decayed.
d. 238U has a longer half-life because more of it have decayed.

Consider a uniformly charged ring in the xy plane, centered at the origin. the ring has radius a and positive charge qdistributed evenly along its circumference. a)what is the direction of the electric field at any point on the z axis? . b)what is the magnitude of the electric field along the positive z axis? use k in your answer, where k=14πϵ0. d)the ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. what will be the angular frequency ω of these oscillations? use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. express your answer in terms of given charges, dimensions, and constants