Relation between velocity and force | Physics Forums
And that tells us if the velocity speeds up the force will be stronger and the radius well be smaller. Only if the (linear) velocity remains the same. The force-velocity curve is simply a relationship between force and velocity and can, therefore, be displayed on an x-y graph (Figure 1). The figure(Figure 1) shows the velocity graph of a object as it moves along the x-axis. What is the net force acting on this object at t=7?.
And they're tiny aliens, their spaceship is only 2. So they gotta pay attention to their speed, but instead of using a speedometer, they clever aliens, they use a force versus time graph. So on their dashboard, they've got a force versus time graph and it tells them what the net force is on them, so let's say this is the net force, not just any force, but this is the total force on them from rocket boosters and the force of gravity and whatever other forces there might be, they've got advanced force sensors.
I mean come on, they can determine their net force, let's say, and it gives them this force as a function of time. But they want to know what is their velocity gonna be after nine seconds? So they check their force versus time readout, and this is the graph they get. And now they can determine it. And here's how they do it. They say, "All right there's a force, a net force "of three newtons acting for the first four seconds. And every alien worth his weight knows that force, the net force multiplied by the time duration during which that force is applied, gives you the net impulse.
So this gives us the net impulse. If we take this constant three newtons that acts, multiplied by four seconds during which it acts, we get that there's an impulse of 12 newton seconds.
And you might be like, "Wait, who cares "about newton seconds here, I want the velocity. And this is good. We know the mass of the object. We wanna know something about velocity.
So we know momentum is M times V, this net impulse is gonna help us get there. But his 12 newton seconds was only for the first four seconds. How do we figure it out for the next three seconds? During the next three seconds, there's not a constant force, this force is varying, the force is getting smaller.
So how do I do this? The force isn't a constant value, so I can't just simply take force times time, because, I mean, what force do I pick? So we're gonna use a trick. We're gonna use a trick, because if you notice for this first section, for the first four seconds, we took the force and multiplied by the time interval, four seconds.
So what we did really is we just took the height of this rectangle times the width of this rectangle and that gives us the area of this rectangle. So what we really did is we found the area under the force versus time graph.
- Introduction to linear momentum and impulse
That gave us the impulse and that's not a coincidence. The impulse equals the area under a force versus time graph, and this is extremely useful to know, because now in this section, where the force was varying, we can still use this, we can just find the impulse by determining the area under that curve.
Force vs. time graphs (video) | Khan Academy
And by area under the curve, we mean from the line curve, in general, to the x-axis, which, in this case, the x-axis is of the time axis. So let's do this. We found the impulse for this first section. That was 12 newton seconds.
Now we can find the impulse for this next section by just determining the area. So this is a triangle. So we get a net impulse of 4. So we've got one more section to go, but this one's a little weird, this one's located, the area is located below the time axis, so this is still a triangle, but since the forces are negative, this is gonna count as a negative net impulse.
Force vs. time graphs
A post shared by Chris Beardsley chrisabeardsley on Feb 8, at This might be achieved by high-velocity strength training. Training with different types of external load could therefore be useful for emphasizing different ends of the force velocity curve.
Using constant resistance or variable resistance could be helpful for improving force at higher velocities. Effects of different strength training regimes on moment and power generation during dynamic knee extensions. Specificity of training velocity and training load on gains in isokinetic knee joint strength.
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