Protons and neutrons are packed together in a very small region called nucleus. Protons are positively charged and we know that like charges repel. Then how is it that protons are not repelling each other and flying away from nucleus?
You may think that gravitational force is holding all the protons together but it is not so. Gravitational force is many times weaker than repulsive force.
It is actually strong force which holds proton together. At this short distance, strong force comes into play and is several times stronger than the repulsive force.
The first one is electrical energy
closed and unsecure circuit
Answer:

Downward
Explanation:
We are given that
Mass of monkey=12.8 kg
Tension=156 N
We have to find the magnitude of the elevator's minimum acceleration.

Where 
Substitute the values



Hence, the acceleration =
Direction of the elevator's minimum acceleration is downward because the elevator moves downwards.