A radioactive isotope of lead has a half-life of 10.6 hours. A small sample of lead containing this isotope has a count rate of 8000 counts per
minute.
How long will it be before the count rate is 1000 counts per minute?
Time =
hours

Astone is thrown with a speed v0 and returns to earth, as the drawing shows. ignore friction and air resistance, and consider the initial and final locations of the stone. which one of the following correctly describes the change δpe in the gravitational potential energy and the change δke in the kinetic energy of the stone as it moves from its initial to its final location? options a.δpe = 0 j and δke = 0 j b.δpe is positive and δke is negative c.δpe = 0 j and δke is positive d.δpe is negative and δke is positive e.δpe = 0 j and δke is negative