The answer is b
Reflection is when a sound wave bounces off a surface back into the medium from which it came.
by definition reflection is the process of change in direction of the wave from a surface at the same angle as it hit the surface. after reflection the wave goes back into the same medium as it came from. also the angle of the wave with surface before and after striking the surface remain same.
It is false that sound waves are the only waves that reflect.
Reflection of the waves means that it is a process when waves hit any object, they bounce off from that object. Sound waves are not the only waves which reflect. Other waves which reflect are infrared waves and the radio waves.
Light waves might move through the material which is known as the process of refraction or might even bounce off the material, hence the light waves may or may not reflect. Thus there are other waves also which reflect from the objects.
b).reverberations in a concert hall
Sound refraction occurs when the sound wave leaves one environment for another, causing a different wave refractive index. This passage ends up causing a change in the speed of propagation and a variation in the length of the sound wave. An example of this can be seen when you recognize reverberations in a concert hall.
This phenomenon does not happen only in sound waves, as it can also be observed in light.
The correct answer is "Light or sound waves change direction"
Refraction: Refraction occurs when a light rays gets bend while travelling from one medium to the another medium due to change in the speed of light or change in the direction. From the given options, the best definition of refraction is "Light or sound waves change direction".
Reflection: Reflection occurs when the light rays get reflected back from the obstacle in a same medium without getting absorb or transmit in it.
From the given options, the best definition of reflection is "Light or sound wave bounce off a medium.
Therefore, the correct option is (A).
a)The balloon is 68 m away of the radar station
b) The direction of the balloon is towards the radar station
We can solve this problem with the Doppler shift equation:
is the actual frequency of the sound wave
is the "observed" frequency
is the velocity of sound
is the velocity of the observer, which is stationary
is the velocity of the source, which is the balloon
(4) This is the velocity of the balloon, note the negative sign indicates the direction of motion of the balloon: It is moving towards the radar station.
Now that we have the velocity of the balloon (hence its speed, the positive value) and the time () given as data, we can find the distance:
(8) This is the distance of the balloon from the radar station