A football quarterback runs 13 m straight down the playing field in 2.2 s (in the positive direction). He is then hit and pushed 2.5 m straight backwards in 1.8 s. He breaks the tackle and runs straight forward another 23 m in 4.8 s. show answer No Attempt 25% Part (a) Calculate the quarterback's average velocity in the horizontal direction during the first interval, in meters per second.

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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.