Answer:
A vacuum
Explanation:
Sound waves are examples of mechanical waves. Mechanical waves are waves which are transmitted through the vibrations of the particles in a medium.
For example, sound waves in air consist of oscillations of the air particles, which vibrate back and forth (longitudinal wave) along the direction of propagation of the wave itself.
Given this definition of mechanical wave, we see that such a wave cannot propagate if there is no medium, because there are no particles that would oscillate. Therefore, among the choices given, the following one:
a vacuum
represent the only situation in which a sound wave cannot propagate through: in fact, there are no particles in a vacuum, so the oscillations cannot occur. In all other cases, instead, sound waves can propagate.
Answer:

Explanation:
We can use the following kinematics equations to solve this problem:
.
Using the first one to solve for acceleration:
.
Now we can use the second equation to solve for the distance travelled by the airplane:
(three significant figures).
<span>Faraday is best known for his work regarding electricity and magnetism. His first recorded experiment was the construction of a voltaic pile with seven ha'penny coins, stacked together with seven disks of sheet zinc, and six pieces of paper moistened with salt water.</span>
Answer:
time of fall and the final velocity
Explanation:
the mass of solid ball is more than the mass of hollow ball.
According to the third equation of motion
v² = u² + 2gh
As the final velocity v does not depend on the mass of the object, so the final velocity of both the ball is same.
According to the first equation of motion
v = u + gt
As v is same for both the balls, the time is also same for both the balls.
So, they both have same time of fall and final velocity.