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antonisz
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Homework Statement
Vehicle A and Vehicle B are moving in opposite directions on the NJTP. Vehicle A is heading south toward atlantic city while vehicle B is heading north towards Hoboken. In situation 1 and 2 described below, at t = 0s both vehicles are at a distance of separation of 400m and are moving towards each other.
Situation 1: When vehicle A is moving at a constant velocity of 30 m/s and travels a distance of 120 m, the vehicles pass each other on the turnpike.
Situation 2: When vehicle A is moving at a constant velocity of 80 m/s and after a time of 3s, the vehicles pass each other on the turnpike.
For vehicle A label variables as: Via, Vfa, aa, da,ta
For vehicle B label variables as: Vib, Vfb, ab,db, tb
In the ORDER INDICATED:
(a) Calculate the initial velocity of vehicle B or Vib; and
(b) Then calculate the acceleration of vehicle B or ab
Show all work in DETAIL and keep all numerical values to the nearest hundredth value. Draw and label all pictures
Note: You will receive NO CREDIT if you first calculate part (b) and then part (a)
For situations 1 and 2
vib = constant ; vfb ≠ a constant value since its value changes w/ time
ab = constant
Homework Equations
The Attempt at a Solution
Situation 1:
Da + Db = 400
Via = 30 m/s
Vfa = 30 m/s
a = 0 m/s2
da = 120 m
ta = ?
Vave = d/ t = vf + vi /2
Vave = da/ta
ta = 4s
db = 280
ta = 4s
Situation 2:
Via = 80 m/s
aa = 0 m/s2
vfa = 80 m/s
ta = 3s = tb
da = ?
Using same equation as in situation 2,
da = 240
db=160
tb = 3s
Situation 1
db = vibtb + 1/2abtb2
280 = vib(4) + 1/2 (ab)(4)2
Situation 2
db = vibtb + 1/2abtb2
280 = vib(3) + 1/2 (ab)(3)2
280 = vi (4) + 8ab
280 - 4bi = 8ab
280 - 4vi/8 = ab
Plug this into the second equation...
160 = vib(3)+ 1/2 (280 - 4vi/8 )9
I solve and get vib = - 4/3 m/s which doesn't make sense...
So i plug that answer back into the two equations above and get ab = 35.67 m/s2 for situation 1 and for situation 2 - 34.67 m/s2.
Thank you for the help