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
Explanation:
Work = force × displacement
532 J = 48 N × d
d ≈ 11 m
Answer:the frequency decreases and the wavelength increases
Explanation:
The frequency decreases and the wavelength increases
Define and measure the speed
choose this
heliocentric theory = Ptolomeu
radioactivity = Becquerel
reflecting telescope - Newton (not sure)
Answer:
Her speed at the bottom of the slide is 7.42 m/s
Explanation:
From the question,
The swimmer starts at rest, that is, her initial speed, u is 0 m/s.
Since she slides without friction and descends through a vertical height, then it is a free fall motion (due to gravity).
Also, from the question,
She descends through a vertical height of 2.81 m.
To determine her speed at the bottom of the slide, that is her final speed,
From one of the equations of motion for freely falling bodies
v² = u² + 2gh
Where v is the final speed
u is the initial speed
g is acceleration due to gravity (g = 9.8 m/s²)
and h is height
From the question,
u = 0 m/s
h = 2.81 m
Putting the values into the equation
v² = u² + 2gh
v² = 0² + 2×9.8×2.81
v² = 55.076
v =√55.076
v = 7.42 m/s
Hence, her speed at the bottom of the slide is 7.42 m/s.