The amount of a sample remaining after t days is given by the equation mc005-1. Jpg, where a is the initial amount of the sample and h is the half-life, in days, of the substance. A sample contains 18% of its original amount of radon-222. The half-life of radon-222 is about 3. 8 days. Which is the best estimate for the age of the sample?.

Ateacher attaches a ball to a meter long string and whirls it around in a horizontal circle at constant speed. the teacher explains that the string is what makes the ball go in a circle. why is the string necessary? a) the string is needed to apply a torque to the ball. b) the string is needed to push on the ball to get it up to speed. c) circle motion requires an inertia which is provided by the string. d) circle motion requires a force to give it a centripetal acceleratio