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A-particle-s-trajectory-is-described-by-x-e-t-e-t-y-2t-Find-the-distance-that-the-particle-traveled-for-0-t-2-




Question Number 103400 by abony1303 last updated on 14/Jul/20
A particle′s trajectory is described by  x=e^t +e^(−t)      y=2t  Find the distance that the particle  traveled for 0≤t≤2
Aparticlestrajectoryisdescribedbyx=et+ety=2tFindthedistancethattheparticletraveledfor0t2
Commented by abony1303 last updated on 14/Jul/20
Pls help
Plshelp
Answered by mr W last updated on 14/Jul/20
dx=(e^t −e^(−t) )dt  dy=2dt  ds=(√((dx)^2 +(dy)^2 ))=(√((e^t −e^(−t) )^2 +4)) dt  =(e^t +e^(−t) )dt  s(t)=∫_0 ^t ds=∫_0 ^t (e^t +e^(−t) )dt=[e^t −e^(−t) ]_0 ^t   =e^t −e^(−t)   ⇒s(2)=e^2 −(1/e^2 )
dx=(etet)dtdy=2dtds=(dx)2+(dy)2=(etet)2+4dt=(et+et)dts(t)=0tds=0t(et+et)dt=[etet]0t=etets(2)=e21e2
Commented by abony1303 last updated on 14/Jul/20
thank you ser. Can you pls explain why   you differentiated x and y, and I can′t  understand the formula in 3rd raw.
thankyouser.Canyouplsexplainwhyyoudifferentiatedxandy,andIcantunderstandtheformulain3rdraw.
Commented by mr W last updated on 14/Jul/20
do you know this:  ds=(√((dx)^2 +(dy)^2 ))=(√(1+((dy/dx))^2 )) dx
doyouknowthis:ds=(dx)2+(dy)2=1+(dydx)2dx
Commented by mr W last updated on 14/Jul/20
if x=f(t), y=g(t),  in time dt the object covers a  distance in x−direction dx=f′(t)dt  and in y−direction dy=g′(t)dt. the  total distance it travels in this time  is ds=(√((dx)^2 +(dy)^2 ))=(√((f′(t))^2 +(g′(t))^2 ))dt
ifx=f(t),y=g(t),intimedttheobjectcoversadistanceinxdirectiondx=f(t)dtandinydirectiondy=g(t)dt.thetotaldistanceittravelsinthistimeisds=(dx)2+(dy)2=(f(t))2+(g(t))2dt
Answered by OlafThorendsen last updated on 14/Jul/20
0≤t≤2 ⇔ 0≤y≤4  x = e^t +e^(−t)  = 2cht = 2ch(y/2)  (dx/dy) = 2×(1/2)sh(y/2) = sh(y/2)  d = ∫_0 ^4 (√(1+((dx/dy))^2 ))dy  d = ∫_0 ^4 (√(1+sh^2 (y/2)))dy  d = ∫_0 ^4 ch(y/2)dy  d = [2sh(y/2)]_0 ^4  = 2sh2 = e^2 −(1/e^2 )
0t20y4x=et+et=2cht=2chy2dxdy=2×12shy2=shy2d=041+(dxdy)2dyd=041+sh2y2dyd=04chy2dyd=[2shy2]04=2sh2=e21e2
Answered by Dwaipayan Shikari last updated on 14/Jul/20
(dx/dt)=e^t −e^(−t)   (dy/dt)=2  Resultant =(√(△x^2 +△y^2 ))=(√((e^t −e^(−t) )^2 +4  ))=e^t +e^(−t)   Time is bounded (0,2)  ∫_0 ^2 e^t −e^(−t) dt=e^2 −(1/e^2 )   (Resultant tracetory)
dxdt=etetdydt=2Resultant=x2+y2=(etet)2+4=et+etTimeisbounded(0,2)02etetdt=e21e2(Resultanttracetory)

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