Velocity is a vector quantity. A vector quantity has both a magnitude and a direction. Speed only has a magnitude, but no direction. Velocity has both.
Let the height where we are trapped is H
now to find the time to reach the key at the bottom is given as

now we have


now if the speed of sound is considered to be 340 m/s then time taken by the sound to reach at the top is given as

now the total time is given as

now by solving above equation we have
H = 48 m
now height of one floor is 3 m
so our position must be

Answer:
It has potential energy
PE = 15450.75 J
Explanation:
we know its potential energy because the carriage is not moving, although it can
PE = mgh
in this case, m is 75, h is 21, and g is always 9.81
plug these in: PE = (75) (21) (9.81)
your answer: PE = 15450.75 J
The answer is B, or endoplasmic reticulum.