what is closing speed? the only information google was able to give me, is that closing speed is when a car is approaching another car both at 30m/s the closing speed is 60m/s, so what exactly is closing speed?
$\begingroup$
$\endgroup$
Add a comment
|
2 Answers
$\begingroup$
$\endgroup$
"Closing speed" is a common-language term meaning the rate at which two objects are getting closer to each other. As a common-language term its meaning is not precise. Usually but not always it implies a collision course. It may mean that the objects are moving straight towards one another, or that they are traveling at an angle to the line connecting them but still on a collision course, or at an angle and not a collision course. It may refer to rate of change of path length along a nonlinear path: for instance, one might describe the closing speed of two automobiles, both driving due north, as being 200 km/h, if they are traveling in opposite directions around a circular track, each at 100 km/h.
One physically precise definition that captures some but not all possible meanings of "closing speed" is the projection of the relative velocity vector onto the displacement vector. (If the projected vector is antiparallel with the displacement, it is a closing speed; if it is parallel it is a separation speed.)
$\begingroup$
$\endgroup$
1
It is the speed of one car relative to another car when they are approaching one another.
Car $A$ moving West at $20\,\rm m\,s^{-1}$ and car $B$ to the East of car $A$ moving West at $60\,\rm m\,s^{-1}$.
Car $B$ is approaching car $A$ at a (closing) speed of $60-20 = 40\,\rm m\,s^{-1}$, ie every second the separation between the cars is reduced by $40\,\rm m$.
