You place a book on top of a spring and push down, compressing the spring by 10 cm. When you let go of the book, it is pushed up by the spring. Which statement describes what happens to the energy of the spring book system?

A. The elastic potential energy of the system increases.
B. The gravitational potential energy of the system increases.
C. The kinetic energy of the system decreases.
D. The total energy of the system increases.

Eliminate D as there is no nonconservative force, then look at each energies before and after. The speed of the book will increase, so kinetic energy is increasing. The height of the book is increasing, so gravitational potential energy is increasing. However, since the spring is becoming decompressed, the elastic potential energy is decreasing.

Explanation:

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.

i don't understand. explain it clearly