A swimmer swims a half lap, moving from the left end to the right end of a pool that is 50 meters long. What is the Distance and Displacement?

Distance = 50m

Displacement = 50m to the right

Distance is the total length of a given path. It is a scalar quantity and thus takes no consideration on the direction of the path.

Displacement on the other hand is the change in position of an object. It is a vector quantity and takes consideration on the direction of the object.

From the question:

The swimmer swims half lap by moving from the left end to the right end of a pool that is 50m long.

Distance = total length of the given path = 50m

Displacement = change in position of the swimmer from the left end (0m) to the right end (50m) = 50 - 0 = 50m

Since direction is important in displacement, the complete details of the displacement should be 50m to the right

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.

real, smaller and upside-down.   so the answer should be b.