what is actually causing the net force as zero? is it because the fluid resistance or upthrust force or both? or is upthrust force and fluid friction is just the same thing?
2006-09-25 21:58:29 · 4 answers · asked by hypnonebula 3 in Science & Mathematics ➔ Physics
so please help me 'unconfuse' myself... shelly
2006-09-25 22:43:19 · update #1
non of you guys really answered my question...
you guys just put your attention in the relationship between force downwards and air friction... what i am actually want to know is... is upthrust force(in liquid) also contribute to the equilibrium between the force downwards and upwards, as well as air friction have contributed to the terminal velocity
2006-09-26 05:35:43 · update #2
When an object falls through the air, it is submitted to two forces:
the gravity, which is directed downward, and the air resistance, which is directed upward.
The force due to gravity is constant: F = m.G (where m is the mass of the object, and G the acceleration due to gravity, on Earth, 9.81 m/s²).
The opposite force, due to air resistance is more complex:
F = k.m.s.e.v², where k is the air "resistance" (friction, drag), m the mass, s the SURFACE aera of the object, normal to the force, e a coefficient of SHAPE (the more pointed the object, the smaller the coefficient), and, the most important factor: v², which represents the VELOCITY of the object.
The force due to gravity is a CONSTANT.
The air resistance, or drag, is not, and depends on the SQUARE of the velocity.
If you were to graph it, with the X axis the velocity and the Y axis the force, the gravitational force would be a horizontal line, at 9.81 on the Y axis, while the drag force would be a half parabola, (the right part of the letter "U") with its minimum at 0,0.
You see that:
1. At start, the drag force is nil, and only gravity acts on the object.
2. As the object falls faster, the drag force increase exponentially.
3. The drag force will intercept the gravitational force at a point, where the two forces are EQUAL.
At that time, the NET force is zero, as both forces are EQUAL and in OPPOSITE direction.
The speed at which it happens is called "terminal velocity" and depends on many factors. It is NOT the same for every objects!
2006-09-25 23:14:22 · answer #1 · answered by just "JR" 7 · 0⤊ 0⤋
the net force of zero is the balance of forces, the down force is gravity, to balnce this you have air resistance, or friction (i think what you say are the same thing), and the air rushing past also causes drag which effects the balance as well, higher speed=more drag+more friction, when this = the pull of gravity (wieght) you reach terminal velocity
2006-09-25 22:07:04 · answer #2 · answered by darren p 2 · 0⤊ 0⤋
Yeah, the fluid friction creates a dynamic force on a falling object. You could call it drag force.
2006-09-25 22:04:18 · answer #3 · answered by craig p 2 · 0⤊ 0⤋
u r confused within urself
2006-09-25 22:32:07 · answer #4 · answered by shelly 2 · 0⤊ 0⤋