Questão sobre conservação da energia mecânica Na figura a seguir um bloco de massa 1,0 kg comprime em 10 cm uma mola cuja constante elástica é k =2000 N/m. Soltando-se o sistema mola-bloco, o bloco percorre a trajetória até atingir a altura de 0,60 m em relação ao nível inicial. Adotando g=10 m/s2, determine a energia dissipada ao longo da trajetória.

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.

iron would move it is magnetic there is a mag field around the current in the wire

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form