Afootball is kicked vertically upward from the ground and a student gazing out of the window sees it moving upward past her at velocity u. the window is a height h above the ground. you may ignore air resistance. how high does the football go above ground?

Explanation:

Let the football is kicked up vertically with some speed given as

now its speed when it will reach to height "h" above the ground is given as "u"

so we will have

here we have

so we have

now we know that when football will reach to maximum height then it will have zero final velocity

So we will have

so we have maximum height given as

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.