A 2-kg object is falling downward with a constant speed of 8 meters per second.?

I guess you are a secondary one or two.

First thing is, there's two basic opposite forces, gravity (g) and normal forces (N). Gravity formula is

w = m . g

where w is weight, m is mass and g is gravitational forces.

But instead of just gravity that points downward (or to the ground), there's an upward forces called Normal Forces. It defies gravity.

The formula is

N = m . g

where N is normal force, m is mass and g is gravity.

Yes, the formula is same. In this case, the answer to your question is

Known : m = 2 kg

v = 8 m/s

but there's one thing g = 10 m/s2

Unknown : N

Solution :

N = m . g

N = 2 . 10

N = 20 Newton

Now, gravitational force always different. Some places in the earth is 10 m/s2 but other 9.8 m/s. Do you know, where is the basic of this Normal Force?

Let's imagine!

Now, earth has its own gravity that pulls us to the ground. But the gravity of the earth is not just pull us, it pulls other object in the space too. That's why a lot of meteors raining on us everyday, because the earth pull them. Thanks to the basic, then other planet also have gravity. and this gravity may pull objects too. Which means their gravity is pulling us as well. But because the gravity rule is "The further the object, the weaker the pull force" then we didn't just pulled to Mars.

Hence, your answer resolved.

If you need further prove, then come and contact me through e-mail or facebook.

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Newton's 2nd law states F=ma

Force acting on 2kg object is F, it's mass is m and a is it's acceleration, in this instance, it is acceleration due to gravity, so it is a = g = 10 m/ s2 approximately.

So force is 2 kg x 10 m/s2 = 20 N

The force of gravity is pushing the object down,so it falls. This force acts towards the ground, so it points downwards.

Newton's 3rd law states every action (force) has an equal and an opposite reaction. So this action which points downwards is reacted by another force hich points upwards, this is equal in magnitude to the action fore, so it is 20 N ( 2kgx10m/s2).

Firstly an object at free fall (falling down) will always be under acceleration and not be at constant speed.Assuming that body falling downwards is at a constant speed or velocity of 8 m/s,

F=ma..........(Newtons II law)

here m is the mass and a is acceleration due to gravity;

thus, F=2 kg*10 m/s^2(assuming g=10 m/s^2)

F=20 kgm/s^2 [or] 20 N;

but every action has an equal and opposite reaction...................(Newton's III law)

therefore to a force of 20 N in the downward direction, there is a reactionary force of 20 N in the upward direction.

There you go that explains it. Hope it helped.......!!!