The speed curves are straight segments and start from the zero position. They start displaced, a segment representing the distance between the mobiles. When they cross, they have different slopes (it couldn´t be other way). They are arcs of parable that start at the initial time with zero slope (horizontal). Look, for example, the kind of curve of the position´s graphs. The graphs always look like four crazy lines.but they are full of information, full of technic. Look how I do them: columned, always in the same order, and with the same time scale some people call this manner "in tandem". With that I´ll go to the third one and comes dĪnd finally, to the two that are missing, from where come the encounter´s speeds If we look the first equation, it has one unknown starting from there, everything turns out much easier. The rest is algebra and is not so dramatic. In it, the unknowns are the ones that the problem ask for.īut really the problem ends here? Here ends the physics of the problem. If all went well, the problem must be solved, let´s see?.Yes, exactly, is written above a system with many equations as unknowns (4x4). They say then:Įstas, en cambio, son las ecuaciones especializadas para los instantes que a vos te interesan. Let´s ask them to "talk" about the encounter. Since the tools are arranged on the table (the time formulas), now we use them. This are the "regular", for every AM To find the ones in our problem we will have to replace the equations´s constants ( t o, x o, v oy a) for the "initials" of each movement.Įstas son las ecuaciones que describen TODO el fenómeno del movimiento que narra el enunciado. X = x o + v o ( t – t o ) + ½ a ( t – t o ) 2 Since here we have two uniformly varied movements, and each AM is described by two equations: Now we ask ourselves ¿How many equations describe this problem? Exactly four. Find:Ī) How much time did the car take to get at the truckī)Initially, what was the distance between themĬ) The speed of each vehicle when they are alongĭ) The position and speed graphs vs time, for both of themįirst of all, as usual, we start with the sketch.Īsí eran los esquemas de No Me Salen cujando los hacía a manopla. Both of them are moving with constant acceleration, 1,8 m/s ² for the car and 1,2 m/s ²for the truck, and they cross over when the car is at 45 meters from its departure spot. KINEMATICS, Uniformly Accelerated Motion Ex 13, EXERCISES OF PHYSICS onlineģ.43 - A car and a truck start simultaneously, from rest, with the car at some distance behind the truck.
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