A runner accelerates from rest with an acceleration of 4.0m/s^2 for 2.3 s. What will her speed be at the end of this time?

u=13

v=30

s/t=u+1\2at

=13+431/2

=13+265.5

=278.5

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.

spectral lines lyman is one set

distance = 150m

displ = root (50 ^2 + 100^2)

root(2500+10000)

root 125000