What is meant by the net force that acts on an object?

Question

1)What is meant by the net force that acts on an object?

2) How do the air resistance and weight of a falling object compare when terminal speed is reached?

Yeah, no idea what-so-ever. Any feedback is greatly appreciated. Thank you.

Answer 1

1) The net force is the sum of all forces that act on the object.

Since forces are vector quantities, their sum, or net force, is a vector sum.

In case of an object falling in the air, the acting forces are the gravity force (weight) W and the air resistance R .The net force is

N = W + R  (N, W, R are vectors)

Since W and R are of opposite directions, the magnitude of their vector sum is the difference of the magnitude of W and R

|N| = |W| - |R|

2) When the terminal speed is reached,i.e. there is no more acceleration, the net force equals 0. The air resistance R and the weight W cancel each other, they have same magnitude but opposite directions.

Answer 2

It means the vector sum of all the forces acting on the object.

weight doesn't change. The apparent weight will be the same as the object's stationary weight, as there is no acceleration.

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Answer 3

1)When an object has a net force, it is either speeding up

   or slowing down.

2) The air drag force "air resistance" on the object is equal to the objects weight: (air drag force - weight)=zero. The object's speed is constant--->The net force is zero.