The frequency of a steam train whistle as it approaches you is 552 hz. after it passes you, its frequency is measured as 486 hz. how fast was the train moving (assume constant velocity)?

Approaching frequency= 552 Hz  

Passing frequency = 486 Hz  

The actual whistle frequency is (552 + 486)/2 Hz = 519 Hz  

Assume the speed of sound = 340 m/s  

Using the Doppler formula: (519/486) -1 = 0.0679

The train speed  = 0.0679 * 340 m/s = 23.09  m/s

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.

multiple allele inheritance is traits controlled by more than 2 alleles (ex: pigeons having 3 alleles of one gene govern their feather color).