Physics Force QUestion?

Question

The force of air resistance acting on a falling object is approximated by the statement that it is proportional to the object's velocity and directed upward. If the object falls fast enough, will the force of air resistance eventually exceed the weight of the object and cause it to accelerate upward? explain......

What about a parachute?

Answer 1

It is possible for an object to be falling fast enough for the force of air resistance to exceed the force of weight and for the object to accelerate upwards until it slows to a speed at which the force of gravity equals the air resistance and the net force equals zero.
However, this will not happen on its own. You cannot drop an object from a tall building and expect to see it accelerate up and down as it falls. As the object accelerates downward, its velocity increases, causing the force of air resistance to increase (meanwhile weight stays constant). The object will approach an equilibrium point at which the air resistance equals the weight and the new force equals zero (speed at this point is called its "terminal velocity"). At this point, the object stops accelerating and travels at a constant velocity until the equilibrium is disturbed. The object cannot cross this equilibrium point on its own...but for example, if you shot a bullet straight down out of a gun, the bullet might exit the gun barrel at a speed such that the drag force is greater than the weight, and the bullet slows down as it falls, approaching the equilibrium point.

Answer 2

The key point that has been missed by everybody is that the force due to air resistance is always opposite to the direction of motion. Therefore, the force due to air friction will NEVER result in an objects velocity being upward.

Answer 3

No, this will never happen, there is a limit to how much force can be exerted via air resistance, and after a certain amound, sorry but can't think of this point exactly, but after this point, the object will fall at a constant velocity to the ground with no acceleration.

Answer 4

Good question. I may be wrong but i think before the resistance has a chance to become greater than the weight, it becomes equal to the weight. At this point, the body stops accelerating and maintains a constant velocity and hence the resistance no longer increases.

Answer 5

No, but it will resist enough to prevent the object from gaining any more speed; called terminal velocity.

Answer 6

at the same time as your question is worded in a tricky way, i'll attempt proper to describe. Gravity speeds up any mass down in direction of the middle of the Earth. that is likewise represented as a stress, as F = mass*acceleration = mg An merchandise sitting on the floor received't flow down, notwithstanding gravity nevertheless acts upon it. hence, to counteract the stress of gravity (that's needed for an equilibrium "static" situation in which the chair isn't transferring), it really is stated that there is an equivalent and opposite stress that pushes up on the chair to counteract the stress of gravity. This stress should be provided through the floor the chair is sitting on. interior a similar way, in case you've been sitting on the chair, you should journey both a stress downward simply by gravity, yet also a stress upward from the chair. hence, both forces cancel out as they're in opposite instructions, and also you do not flow up or down.