The discovery of Uranus, Neptune, most asteroids, the moons of
any planet other than Earth, Pluto, and all the other dwarf planets,
required the invention and use of telescopes. Those objects are all
too dim to be seen with a bare naked human eye.
Saturn is bright and plainly visible with your eyes, if you know when
and where to look, and what you're looking at.
Answer:
a) t = 0.75 s, b) t = 2.25 s
Explanation:
The speed of sound is constant in a material medium
v = 340 m / s
we can use the relations of uniform motion to find the time
v = x / t
t = x / v
In the exercise, the observer's distance to the wall is indicated d = 510 m, it also indicates that the shot is fired at the midpoint
x = d / 2
a) direct sound the distance from the observer to the screen is
x = 510/2 = 255 m
t = 255/340
t = 0.75 s
b) echo sound.
In this case the sound reaches the wall bounces, the distance is
x = d / 2 + d
x = 3/2 d
x = 3/2 510
x = 765 m
the time is
t = x / v
t = 765/340
t = 2.25 s
A this refers to the make up of the soil
