PADI Physics and Gas Laws 3

Question 1

A flexible balloon contains 6 liters of air at the surface. What volume will it have at 66 feet (20 m, 3 ATA)?

Accepted Answer

2 liters

Answer

Boyle's Law: V2 = (P1 × V1) / P2 = (1 × 6) / 3 = 2 liters.

Question 2

The term 'partial pressure' refers to:

Accepted Answer

The pressure contributed by a single gas in a mixture

Answer

Dalton's Law defines partial pressure as each gas component's individual contribution to total pressure.

Question 3

At what partial pressure of oxygen does acute CNS oxygen toxicity become a significant risk during diving?

Accepted Answer

Above 1.6 ATA

Answer

PADI guidelines set 1.6 ATA ppO2 as the maximum limit for recreational diving to avoid CNS oxygen toxicity.

Question 4

Light refraction underwater makes objects appear:

Accepted Answer

Closer and larger than they actually are

Answer

Due to refraction at the mask lens interface, objects underwater appear about 25% closer and 33% larger than actual.

Question 5

Sound travels underwater approximately how much faster than in air?

Accepted Answer

4 times faster

Answer

Sound travels roughly 1,500 m/s in water compared to about 340 m/s in air — approximately 4 times faster.

PADI - Professional Association of Diving Instructors Practice Test