Two objects with the same mass move with the same speed but in opposite directions. A. Kinetic energies are equal B. Kinetic energies are opposite in magnitude C. Kinetic energies of the higher objects is greater D. Kinetic energy of the lower object is greater

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When two objects collide there will be a force acting on them both and their individual kinetic energies and momenta may alter. As you know already, energy is always conserved but in a collision some, or all of the kinetic energy may be ... of the same mass and traveling at the same speed but in opposite directions collided ...

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.