Answer:
1. t = 3.27 seconds
2. y = 147.3 m
Explanation:
Newton's Laws of Motions.
y = v₁t + 1/2 at²
a = (v₂-v₁)/t
where
y = the vertical distance travelled
v₁ = the initial velocity
v₂ = the final velocity
t = the time
a = the acceleration
final velocity is equal to 0.
So, v₂ = 0.
a = (v₂-v₁)/t
a = (0-30)/t
a = -30/t
plugin values into the first equation:
y = v₁t + 1/2 at²
49 = 30t + 1/2 (-30/t)t²
49 = 30t -15t
49 = 15 t
t = 49/15
t = 3.27 seconds
2.
y = v₁t + 1/2 at²
a = -30/3.27
a = 9.2
y = 30(3.27) + 1/2(9.2) 3.27²
y = 147.3 m
Answer:
= 15 m/s
Explanation:
Considering right side(west) as positive x-axis and south as negative y-axis.
velocity of boat in still water 
velocity of stream 
now relative velocity of boat w.r.t. stream 
this velocity with which ac distance will be covered.
therefore magnitude of 
= 15 m/s
This is a speed/time graph.
The slope of the graph at each point is the time rate of change of speed
at that point, and THAT's the definition of the magnitude of acceleration.
The slope of the curve is zero at both ' A ' and ' B ', so acceleration is
zero at both of those points.
That seems to be exactly what choice-c says.
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