The earth exerts the necessary centripetal force on an orbiting satellite to keep it moving in a circle at constant speed. which one of the following statements best explains why the speed of the satellite does not change although there is a net force exerted on it?
a) the satellite is in equilibrium.
b) the acceleration of the satellite is zero m/s2 .
c) the centripetal force has magnitude mv2 /r.
d) the centripetal force is canceled by the reaction force.
e) the centripetal force is always perpendicular to the velocity.

E) The centripetal force is always perpendicular to the velocity.

Explanation:

Due to gravity and inertia, the satellite follows a uniform circular motion. In this movement, the velocity is always tangent to the orbit and the centripetal force is directed towards the center. Therefore, there is no net acceleration in the same direction of velocity, which implies that it remains constant.

b. latent learning (the word "latent" itself means something that exists but isn't obvious, only under certain conditions! )

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.