Abox of bananas weighing 40.0 n rests on a horizontal surface. the coefficient of static friction between the box and the surface is 0.40, and the coefficient of kinetic friction is 0.20. (a if no horizontal force is applied to the box and the box is at rest, how large is the friction force exerted on the box? (b what is the magnitude of the friction force if a monkey applies a horizontal force of 6.0 n to the box and the box is initially at rest? (c what minimum horizontal force must the monkey apply to start the box in motion? (d what minimum horizontal force must the monkey apply to keep the box moving at constant velocity once it has been started? (e if the monkey applies a horizontal force of 18.0 n, what is the magnitude of the friction force and what is the box's acceleration?

https://www.physicsforums.com/threads/monkey-friction.182280/

Explanation: look here

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.

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