Why are bridges declared unsafe after a long use
1 answer:
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Answer:
Explanation:
a) KE = (1/2) * m * () = F * d = 14m * 200N = 2800 m/N or 2.8 *
m/N
b) 0J and 0m/s (if Marcella stopped after going 14 meters)
c) Known from part (a) that KE = 2800 J = F1 * d1,
2800J = F1 * (14m - 1m) => F1 = 2800J/13m = 215.384 N
Answer:
d = 142.5 m
Explanation:
This is a vector exercise. Let's calculate how much the boat travels in the 40s
d₀ = t
d₀ = 0.75 40
d₀ = 30 m
Let's write the kinematic equations
Boat
x = d₀ + t
x = 0 + t
At the meeting point the coordinate is the same for both
d₀ + t =
t
t ( -
) = d₀
t = d₀ / ( -
)
The two go in the same direction therefore the speeds have the same sign
t = 30 / (0.95-0.775)
t = 150 s
The distance traveled by man is
d = t
d = 0.95 150
d = 142.5 m