Aballoon of mass m is floating motionless in the air. a person ofmass less than m is on a rope ladder hanging from the balloon. the person begins to climbthe ladder at a uniform speed v relative to the ground. how doesthe balloon move relative to the ground?
a. up with speed v
b. up with a speed less than v
c. down with a speed less than v
d. down with speed v

Correct answer letter C.

Explanation:

As we see in this problem, the total linear momentum is conserved, since there are no external forces acting in that system.

So, we can say that or

Now, the initial momentum is zero, because before the person starts climbing, the system (balloon plus person) are floating motionless, therefore we have:

 (1)

We know that M > m, therefore, m/M < 1 and using (1) we can deduce that V(balloon) < v(person).

Finally, we can say that the balloon moves down (because of the minus sign of V(balloon)) and its speed is less than v(person). Correct answer letter C.

I hope it helps you!  

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.

this could be newton#'s law of cooling. the cooling curve is exponential