Let the mass of 2500 kg car be
and it's velocity be
and the mass of 1500 kg car be
and it's velocity be
.
After the bumping the mass be M and it's velocity be V.
By law of conservation of momentum we have

2500 * 5 + 1500 * 1=4000 * V
V = 14000/4000 = 7/2 = 3.5 m/s
So the velocity of the two-car train = 3.5 m/s
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Answer:
a) Not Accurate
b) Not Accurate
c) Accurate
d) Accurate
Explanation:
Part a
Not Accurate, because destructive interference would lead to maximum possible magnitude of < 3 m
Part b
Not Accurate, because constructive interference would lead to minimum possible magnitude of > 2 m
Part c
Accurate, because destructive interference would lead to maximum possible magnitude of < 3 m by varying the phase difference between two waves she can achieve the desired results.
Part d
Accurate, because constructive interference would lead to minimum possible magnitude of > 2 m by varying the phase difference between two waves she can achieve the desired results.