How many joules are expended by a 70 kg man climbing up 6m of stairway? How much work is done if the climbing takes place on the surface of the moon? (Assume that the acceleration due to gravity on the moon’s surface is 1.6 m/s2

On the earth surface ,W= 4200 J

On the moon surface ,W= 672 J

Explanation:

Given that

mass of the man ,m = 70 kg

Height of the stairway ,h= 6 m

On the earth surface :

We know that acceleration due to gravity at earth ,g= 10 m/s²

The work done by man is given as

W= m g h

Now by putting the values in the above equation we get

W= 70 x 10 x 6 J

W=4200 J

On the moon  surface :

The gravity on the moon ,g= 1.6 m/s²

The work done W

W= 70 x 1.6 x 6 J

W=672 J

On the earth surface ,W= 4200 J

On the moon surface ,W= 672 J

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.

positive reinforcement? ?