Answer:
A. The sound wave will reflect off Buildings and automobiles.
Explanation:
This is because the sound waves would more likely propagate through diffraction through buildings and transmission through the air. It is also more likely to be absorbed by buildings than for multiple reflections to occur off buildings and automobiles. In the process of reflection, these materials would absorb the sound energy thereby reducing its ability to reflect.
Answer:
The minimum speed required is 5.7395km/s.
Explanation:
To escape earth, the kinetic energy of the asteroid must be greater or equal to its gravitational potential energy:

or

where
is the mass of the asteroid,
is its distance form earth's center,
is the mass of the earth, and
is the gravitational constant.
Solving for
we get:

putting in numerical values gives


in kilometers this is

Hence, the minimum speed required is 5.7395km/s.
Answer:
7.5 km/h (2.1 m/s) due east
Explanation:
The average velocity of the person is given by:

where
d is the displacement
t is the time taken
In this problem,
d = 15 km is the displacement
t = 2.0 h is the time elapsed
so the average velocity is

and the direction is the same as the displacement (east).
We can also convert the velocity into SI units (m/s). We have:
d = 15 km = 15,000 m
t = 2.0 h * 3600 s/h = 7200 s

Answer:
Only the hydrogen needs to be balanced. There are equal numbers of aluminum and chlorine.
Explanation:
I took the K12 test, listened to some other idiot and got it wrong, so this is the correct one.
Hope this helps!