Naturally occurring uranium is a mixture of 238u (99.28%) and 235u (0.72%) isotopes. i) how old must the material of the solar system must be if one assumes that at its creation both isotopes were present in equal quantities? how do you interpret this result? the age of the planet earth is estimated at 4.5 billion years. the lifetime of 235u is t235 = 1.015 ~ 109 years. the lifetime of 238u is t238=6.49 ~ 109 years. ii) obtain the fraction of the initial 238u amount that has decayed since the formation of the earth's crust 2.5 x 10'years ago?

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.