(a) suppose that a nascar race car is moving to the right with a constant velocity of +82 m/s. what is the average acceleration of the car? (b) twelve seconds later, the car is halfway around the track and traveling in the opposite direction with the same speed. what is the average acceleration of the car?

Acceleration is the change in velocity. Since the car is moving with the constant velocity it has no acceleration.
the car has no acceleration. Since there is still no change in the velocity of the car. 

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.

c

explanation: