<h2>
Answer: an underground lake</h2>
Explanation:
In general, sound (mechanical waves) travels faster in solids than in liquids, and faster in liquids than in gases. This is because <u>the speed of the mechanical waves is determined by a relationship between the elastic properties of the medium </u>in which they are propagated and the mass per unit volume of the medium (that is:<u>density</u>).
In other words: The speed of sound varies depending on the medium through which the sound waves travel.
So, if we are told the sound wave initially had a speed of 4,000 m/s and it suddenly decreases to 1,500 m/s, this means the sound waves passed from a solid medium to a liquid medium.
Hence, the correct option is: an underground lake.
I’m pretty sure it’s D. variable
Answer:
2 m/s
Explanation:
The total time = 1 hour
The vertical displacement = 1 - 1
Vertical displacement = 0
Horizontal displacement = 4 - 2
Horizontal displacement = 2
Total displacement = sqrt (2^2 - 0^2)
Displacement - 2
Average velocity is displacement/time
= 2x1
= 2 m/s
The average velocity is 2 metres per second.
A "light year" is not an amount of time.
It's an amount of distance ... the distance that light travels
through space in one year.
1 light year = 5,878,625,372,000 miles
(rounded to the nearest thousand miles)
1 light-year = 9,460,730,473,000 kilometers
(rounded to the nearest thousand kilometers)
Answer:
The magnetic field produced by a long straight current-carrying wire is directly proportional to the current in the wire and inversely proportional to the distance from the wire.
Explanation:
The magnetic field produced by a long straight current-carrying wire is given by :
............(1)
Where
= permeability of free space, 
I = current flowing in the wire
d = distance from wire
From equation (1), it is clear that the magnetic field produced by a long straight current-carrying wire is directly proportional to the current flowing and inversely proportional to the distance from the wire. So, the correct option is (d).
