If you're on the ground floor at an apartment block and you saw a woman slipped and fell from the 11th flr, would tackling her save her?

No. She was falling at nearly 55 mph when she hit the ground. There is no way we can deal with that amount of kinetic energy in such a short time with a puny human body. Kinetic energy goes up by the square of the speed, power is energy divided by time, and time decreases in proportion to speed. Because of that the power required is 11^3=1331 times the power required to arrest the fall if she had merely fallen off the roof of her one story house.

While doing tower work the last step in derigging is to drop the bucket of tag line (3/8 inch rope). When dropped from a hundred feet, less than the woman fell, the 15 lb bucket (about a tenth the weight of the woman) makes a fierce WHAP! when it hits the ground. More to the point, I worked with a man who didn't take safety seriously enough and fell 20 feet, landing on his feet on hard packed earth. He was badly injured, including several fractured vertebrae and two shattered ankles.

The first rule of emergency response is "don't increase the casualty count." If you see anybody falling from more than a low ladder, get out of the way.

If she was more than a couple of stories up, your best course of action would be to get far enough away you won' be hurt by debris when she hits. Ever at 30 feet she's coming down at 60MPH or so. That's a LOT of inertia and energy for a 100+ pound object! The acceleration due to the force of gravity is 32 feet per second, per second. Inertia increases at the square if the increase in speed. Get the hell outta the way!!!

I'm not good with physics either, I took biology.

But if my assumption is correct, it is all to do with the kinetic energy of the woman.

When she falls, gravity pulls her down and increases her speed; increasing kinetic energy.

In order for her to survive, the energy needs to be low enough that her internal organs do not suffer fatal damage. Air resistance is not great enough from that distance, and neither would a man stretching out his arms.

You see those crash mats they use for suicide jumpers? They are large and spongy so to absorb the energy of the impact and spread it across the mat. Without it, you would hit the ground and the force of the impact would crush your body and fatally damage organs.

No, taking into account the weight of an adult and the speed and height and which they're falling, tackling her/catch her etc would result in her still dying and you getting very very hurt.

Tackling her will save her but also might hurt her and you. Both of you could hurt your head because the hard impact on the ground. It would be better to catch her and place her down safely.

Anything that breaks the fall could help, but the danger is that, by trying to catch the person, divert them, or break the fall, the person who attempts that could place her or himself in danger and both might be killed.

Adding a horizontal vector would not change the vertical vector at all.

That man is a hero. Stupid, but still a hero.

No the energy she is carrying would be split between you and you`d both be badly injured.

I won't be that heroic man.