What is the definition of net force?

Answer 1

Suppose m is the mass of body moving under the influence of a set of forces (with magnitudes and directions) as specified.
e.g. let us visualize a RAINDROP

(1) F1= mg, acting downwards
(2) F2= up thrust due to medium (buoyancy - cloud) and volume
of drop = vol*(rho-m)*g
(3) F3=drag of medium (stroke' force) upwards 6 pi *eta*r* velo

Now you have to decide where the expected movement of m is desired (e.g. raindrop cannot go up). Thus, take cloud as ORIGIN and expected direction of fall as (+x).

Of course, m will be tested for its accelerated motion downwards so READILY prepare your

[m*d^x/dt^2] downwards (positive, ready to lead m with acceleration x-double DOT)
>> it just like the probe-end of a radiologist performing ultrasound of pregnancy.

All F1, F2 and F3 >> now become subjugate to it [ ], and will be treated with + or minus relative to [ ] positive. In other words,

(+ F1), (- F2) and (- F3) all downwards

so NET FORCE = [m*d^x/dt^2] = + F1 - F2 - F3

The drop will fall when m*d^x/dt^2 = net positive or F1>(F2+F3)
F2 up thrust depends on variation in geometrical properties (vol) in nature - a limited variant. It so happens that stroke's drag (ETA-viscosity coeff remains stubborn in vapor phase - varies odd powers of temp than phase changed water) has to be cut off so that F3 falls drastically. Raindrops show us the positive net force downwards.

For clear picture of motion, writing a similar differential equation is a must.

When net force on m is =0 then m*d^x/dt^2=0
dx/dt =constant

if m*d^x/dt^2=0 after time "t" (or during transit) then net force (F1, F2, F3) has algebraically forced m to stop accelerating, thus acquire Terminal velocity.

you have to visualize this DE in every case.

Answer 2

It is the total force or the sum of all the forces acting on something. According to Newton's second law it is also equal to ma. So if you know an object's mass and it's accelertation, you know the net force acting on it.

Answer 3

The net force is the sum of all forces.

Answer 4

When two or more forces acts upon a body in magnitude and direction, and add the force vectorially

Answer 5

Unbalanced force is another way to put it. 2 left plus one right= 1 left.