Answer:
0.11m
Explanation:
let's assume the boat is of uniform construction
Ignoring friction losses
Also assume the origin is at the end of the boat originally with the heavier person
the center of mass of the whole system will not change relative to the water when the two swap ends
Originally, the center of mass is
85[0] + 90[3.5/2] + 50[3.5] / (85 + 90 + 50) = 1.14m from the origin
after the swap, the center of mass is
50[0] + 90[3.5/2] + 85[3.5] / (85 + 90+ 50) = 1.030m from the origin
The center of mass has shifted
1.14-1.030 = 0.11m
as no external force acted on the system, the center of mass relative to the water will not change. The boat will therefore shift towards the end where the heavier person originally sat
Down stream it would be going 20 mph and up stream 10 mph
initial velocity of the car given as

final velocity is given as

as we know that

now we can convert final speed into m/s

now acceleration is rate of change in velocity



so the acceleration of the car is 3 m/s^2
The velocity of the girl is -4.8 m/s.
Using the principle of conservation of linear momentum, The total momentum of bodies before and after collision is constant. Since the two objects are stationary, the initial momentum of each body is zero.
Thus;
0 = (80 × 3) + (50 × v)
0 = 240 + 50 v
-240 = 50 v
v = -240/50
v = -4.8 m/s
Note that the negative sign shows that the velocity of the girl is in opposite direction that that of the girl.
Learn more about momentum: brainly.com/question/904448