3 ms·
> the equation in Newton’s second law isn’t F = ma, but rather the more subtle statement that force is equal to the rate of change of momentum of a body This i
by ta1234567890 7y ago
> the equation in Newton’s second law isn’t F = ma, but rather the more subtle statement that force is equal to the rate of change of momentum of a body
This is probably the most insightful bit and points directly to the potential of fiddling with the equation.
Drawing an analogy from electricity, F=ma is in a way the "DC version/expression" of a force, in which m and a are constant and F is a fixed quantity. However we can write an "AC version/expression" of the equation as F(t)=m(t)*a(t), in which the average of F(t)=F.
In a way we tend to just be content with dealing with averages instead of looking at the detail and seeing how it varies over time.
There's a lot of potential in looking at the variation. Especially as technology enables it through high speed cameras and instruments with higher sampling rates/resolution.
- raverbashing 7y agoThe "AC" version of that equation is actually F=dp/dt (p = momentum)
- ta1234567890 7y agoThank you for the formula. Do you know of example advances that have been made or problems that have been solved as a consequence of applying the concept implied in that formula?
- ianopolous 7y agoRockets
- ta1234567890 7y agoCare to elaborate?
- aerodude 7y agoRockets have an exhaust with constant velocity, and they expel mass in the form of fuel. It's this expulsion of mass that generates the force that propels the rocket. Taking a force balance and assuming no external forces (e.g. gravity), you can integrate to get the rocket equation, which tells us how much fuel mass we need to reach a given velocity (the quantity we care about when talking about stellar distances).
- jcims 7y agoWait, is acceleration change in velocity or momentum? Presumably these begin to diverge in a relativistic frame of reference?