Many people assume air resistance acting on a moving object will always make the object slow down. It can, however, actually be responsible for making the object speed up. Consider a 180-kg Earth satellite in a circular orbit at an altitude of 205 km. A small force of air resistance makes the satellite drop into a circular orbit with an altitude of 80 km. (Use the following values: G = 6.67 10-11 m3 kg−1 s−2, mass of the Earth 5.98 1024 kg, radius of the Earth 6.37 106 m.)

Many people assume air resistance acting on a moving object will always make the object slow down. It can, however, actually be responsible for making the object speed up. Consider a 180-kg Earth satellite in a circular orbit at an altitude of 205 km. A small force of air resistance makes the satellite drop into a circular orbit with an altitude of 80 km. (Use the following values: G = 6.67 10-11 m3 kg−1 s−2, mass of the Earth 5.98 1024 kg, radius of the Earth 6.37 106 m.)

(a) Calculate the satellite's initial speed.  m/s

(b) Calculate its final speed in this process.  m/s

a)

b)

Explanation:

Given that;

The Earth satellite = 180-kg

altitude (radius r ) = 205 km

After the satellite drop into a circular orbit; the final altitude (r) = 80 km

G =

mass of the earth =

radius of the earth =

The original speed for both circular orbit is given as:

(a) Calculate the satellite's initial speed m/s

v = 7729.88

v =

b) Calculate its final speed in this process m/s

v =7804.42

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.