A) Pitch depends on the frequency of a sound wave. The higher the pitch, the higher the frequency and the lower the pitch, the lower the frequency. Sound waves have different pitches due to varying frequency levels.
B) Sound is created as the pen vibrates. This vibrations also interacts with the air atoms and molecules, causing them to vibrate too, therefore, creating sound waves. The reason the brain grows annoyed at this continual sound is because the brain will focus on this sound only, causing the brain to go into overdrive, creating annoyance.
C) Sound waves are travelling vibrations of particles. Space does not have any atoms or particles for the sound vibrations to interact with, therefore creating zero sound waves to travel.
Hope this helps!! :))
Answer:
Part a)

Part b)
Ball thrown downwards =
Ball thrown upwards =
Part c)

Explanation:
Part a)
Since both the balls are projected with same speed in opposite directions
So here the time difference is the time for which the ball projected upward will move up and come back at the same point of projection
Afterwards the motion will be same as the first ball which is projected downwards
so here the time difference is given as



Part b)
Since the displacement in y direction for two balls is same as well as the the initial speed is also same so final speed is also same for both the balls
so it is given as




Part c)
Relative speed of two balls is given as


now the distance between two balls in 0.8 s is given as



Its a thermometer . i hope this helps you
Resistance per 1000 feet for gauge 14 wire is given as
R = 2.525 ohm
now if wire is of length 50 feet only then the resistance is given as


now if 11 A current flows through the wire then the voltage drop is given by ohm's law



so most appropriate answer in given options is
A. 1.8 Volts
A. The molecules start packed together very tightly in a solid. Then when it turns to water, the molecules can move around each other freely, but still contained. When water turns to vapor, the molecules are going crazy moving around. They are not contained at all and bounce of of each other freely.
b. The temperature rises. (ice turns to water at 33 degrees and water turns to vapor at 212 degrees)