Using local acceleration of gravity data from the Internet, de- termine the weight, in N, of a person whose mass is 80 kg living
1 answer:
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Answer:
(a) 0
(b) 10ML
(c)
(d)
Explanation:
(a) When hanging straight down. The child is at the lowest position. His potential energy with respect to this point would also be 0.
(b) Since the rope has length L m. When the rope is horizontal, he is at L (m) high with respect to the lowest swinging position. His potential energy with respect to this point should be
where g = 10m/s2 is the gravitational acceleration.
(c) At angle from the vertical. Vertically speaking, the child should be at a distance of
to the swinging point, and a vertical distance of
to the lowest position. His potential energy to this point would be:
(d) at angle from the horizontal. Suppose he is higher than the horizontal line. This would mean he's at a vertical distance of
from the swinging point and higher than it. Therefore his vertical distance to the lowest point is
His potential energy to his point would be:
Answer:
The lifeguard takes 25.9 seconds to reach the child, at 25.9 meters from the start point downstream.
Explanation:
As the image shows, the child trajectory, the lifeguard trajectory and the distance from the bank form a triangle. This triangle is formed by the distances, an we already know the distance from the bank and the speed of child, and the speed of the lifeguard. So we have unknom time in common. Lets see the equations:
Using phitagoras theorem
