For rotational equilibrium of the door we can say that torque due to weight of the door must be counter balanced by the torque of external force

here weight will act at mid point of door so its distance is half of the total distance where force is applied
here we know that

now we will have


so our applied force is 72.5 N
Answer:
A nuclear winter is a climatic phenomenon that would follow the detonation of several atomic bombs in the event that a nuclear war broke out. These bombs would cause firestorms that would raise smoke, dust and particles into the atmosphere that would end up in the stratosphere and eventually spread throughout the globe.
Explanation:
That idea is far fetched, because even though those same particles would absorb sunlight, it would raise the temperature in the stratosphere and cause a decrease in temperature in the Earth's layer. Unable to seep the sun's rays, many plant species would die and this would affect the entire food chain.
In addition, that temperature rise in the stratosphere would destroy part of the ozone layer, causing greater exposure to ultraviolet rays. This would end up affecting health and further damaging plant species.
As per FBD while its accelerating upwards
we can say that

here normal force is given as


now mass is given as


now we will have


Now while accelerating downwards we can say by FBD

again plug in all values

