The time difference between their landing is 2.04 seconds.
<h3>
Time of difference of the two balls</h3>
The ball thrown vertical upwards will take double of the time taken by the ball thrown vertically downwards.
Time difference, = 2t - t = t
t = √(2h/g)
where;
- h is the height of fall
- g is acceleration due to gravity
Apply the principle of conservation of energy;
¹/₂mv² = mgh
h = v²/2g
where;
h = (20²)/(2 x 9.8)
h = 20.41 m
<h3>Time of motion</h3>
t = √(2 x 20.41 / 9.8)
t = 2.04 s
Thus, the time difference between their landing is 2.04 seconds.
Learn more about time of motion here: brainly.com/question/2364404
#SPJ1
<span>C. waves can only interfere destructively. </span>
The wavelength of a sound wave is related to its frequency by the relationship:

where
f is the frequency
v is the speed of the wave

is the wavelength
The wave in our problem has wavelength of

and speed of

(this is the speed of sound in air), therefore its frequency is

And the period of the wave is equal to the reciprocal of its frequency:
The mass needed at peg 1 is a 5g mass.
The 15g should hang at peg 5.
The reason is force x distance clockwise is equal to force x distance anti-clockwise