The radioactive isotope technetium-99 in an excited state ( 9943tcm or tc-99m) can be used in medicine to determine a patient's blood volume. tc-99m emits gamma-rays and has a half-life t1/2 = 6.0h. a sample of tc-99m of mass 7.7x10-14kg is injected into the patient's circulatory system. 1.0 h after the injection, 20 cm³ of blood is taken from the patient. the activity of this sample is measured to be 55 kbq. calculate the patient's blood volume. show with explanations.

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?

A14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.

The protons in a nucleus are approximately 2 ✕ 10^−15 m apart. consider the case where the protons are a distance d = 1.93 ✕ 10^−15 m apart. calculate the magnitude of the electric force (in n) between two protons at this distance.