Astudent pushes a 10 kg box with a force of 30 n at an angle 45 degrees below the horizontal . the box experi 21.2 n of force against the motion. what is the acceleration of the box?

Acceleration =0

Explanation:

There are two forces on the box in horizontal direction.

First one is horizontal component of 30N at 45°.

Another one is given in opposite to direction of motion mean opposite to this force.

Which is = 2.22 N

Now we know F (net) =mass*acceleration(center of mass)

21.2-21.2 =10*acceleration

acceleration =0

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.

the answer is kevlar