Power = Work done / Time taken.
Work done = mgh
Mass, m = 33kg ( Am presuming it is 33 kg).
h = 85 m.
Work done = 33 * 9.81* 85 = 27517.05 J.
Time taken.
Since object was dropped from height, it fell under gravity.
Using H = ut + (1/2) * gt^2. u = 0.
H = 1/2 gt^2.
t = (2H/g) ^ (1/2)
t = (2*85/9.81) ^ 0.5 = 4.1628 s.
Power = 27517.05 / 4.1628 = 6610.23 Watts.
= 6610 W to 3 S. f.
Answer: D.
Explanation: Just took the quiz.

Since the sound travels from the submarine to the object AND back, it actually travelled 3625x2=7250m.

Speed of sound: 1450m/s
Answer
B. X
A plate of glass or metal ruled with very close parallel lines, producing a spectrum by diffraction and interference of light.
diffraction grating is an optical component that splits and diffracts light into several beams travelling in different directions. The light emerges with its colours separated.