Two identical discs are spinning on a vertical rod, at different rotation rates. The bottom disc is on a support, and the top disc is sliding down to hit the bottom one. Two discs are on a narrow vertical pole. The bottom disc is supported, while the top disc slides down. They're spinning at two different rotation rates. Once they hit, they rotate together as a single object. Calculate the rotation rate just after the collision, in rev/s. Bottom rotation rate: 5800 rev/s Top rotation rate: 10600 rev/s Mass 430 grams Radius 19 cm

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

your answer is c! hope this : )