Answer:
4.7m
Explanation:
Given parameters:
Mass of the book = 1kg
Gravitational potential energy = 46J
Unknown:
Height of the shelf = ?
Solution:
The potential energy is due to the position of a body above the ground.
Gravitational potential energy = mgh
m is the mass,
g is the acceleration due gravity = 9.8m/s²
h is the height which is unknown
46 = 1 x 9.8 x h
h = 4.7m
Answer:
Black is the result of absorbing all colors with different wavelengths. No light is reflecting off it that we can see. So we can see it in white because as far as our eyes, there is just enough contrast in the light against the white for the print to be visible.
<h2>
The speed of the rock just before it reaches the water 25.0 m below the point where the rock left your hand is 45.06 m/s</h2>
Explanation:
First let us find the initial velocity,
We have after 8 seconds the displacement is zero,
We have equation of motion s = ut + 0.5 at²
Initial velocity, u = ?
Acceleration, a = -9.81 m/s²
Time, t = 8 s
Displacement,s = 0 m
Substituting
s = ut + 0.5 at²
0 = u x 8 + 0.5 x -9.81 x 8²
u = 39.24 m/s
Initial velocity is 39.24 m/s.
Now this case is similar to case where a rock is thrown at 39.24 m/s downward.
We have equation of motion v² = u² + 2as
Initial velocity, u = 39.24 m/s
Acceleration, a = 9.81 m/s²
Final velocity, v = ?
Displacement, s = 25 m
Substituting
v² = u² + 2as
v² = 39.24² + 2 x 9.81 x 25
v = 45.06 m/s
The speed of the rock just before it reaches the water 25.0 m below the point where the rock left your hand is 45.06 m/s
Well, that's not actually "diffraction".
The fuzzy edge of the moon, and the added glow that's sometimes seen
around it, are all effects caused by the light passing through air before it
reaches you.
This gives you some idea of why astronomers go to such effort and
expense to get their telescopes above as much of the atmosphere as
possible ... placing all serious observatories on mountaintops, and even
putting telescopes in orbit. It's all because the air does such a job on the
light that's trying to shine through it. We have to make do with whatever's
left over after that.