1.8 Pressure (3)
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1.
A diver is at a depth of 10 metres in seawater. The density of seawater is approximately 1025 kg/m3. Explain, qualitatively, why the pressure experienced by the diver at this depth is greater than the atmospheric pressure at sea level.
The pressure experienced by the diver at 10 metres in seawater is greater than atmospheric pressure at sea level because the diver is subjected to the weight of the seawater above them.
Atmospheric pressure is the pressure exerted by the air in the atmosphere. As the diver descends, they are surrounded by an increasing volume of seawater. This seawater has a mass, and the weight of this mass exerts a pressure on the diver.
The pressure exerted by a fluid is directly proportional to its density and the depth. Seawater is denser than air, meaning it has more mass per unit volume. Therefore, the weight of the seawater above the diver is greater than the weight of the air above sea level. This greater weight results in a higher pressure experienced by the diver.
In essence, the pressure at a given depth is the sum of the atmospheric pressure and the pressure due to the weight of the fluid above. Since the diver is at a significant depth, the pressure due to the seawater is substantial and exceeds atmospheric pressure.
2.
A balloon has a surface area of 0.5 m². The internal pressure of the balloon is 1.2 atmospheres. Convert the internal pressure of the balloon to Pascals (Pa). (1 atmosphere = 101325 Pa). Show your working.
Given:
- Surface Area (A) = 0.5 m²
- Internal Pressure (P) = 1.2 atmospheres
- 1 atmosphere = 101325 Pa
Conversion:
P (Pa) = P (atm) x 101325 Pa/atm
P = 1.2 atm x 101325 Pa/atm = 121590 Pa
Answer: The internal pressure of the balloon is 121590 Pa.
3.
A student is investigating pressure. They use a lever to lift a weight. The force applied to the lever is 50N and the area of the surface on which the force acts is 0.2 m². Calculate the pressure exerted by the weight on the surface. Show your working.
Given:
- Force (F) = 50 N
- Area (A) = 0.2 m²
Equation:
Pressure (p) = F / A
Calculation:
p = 50 N / 0.2 m² = 250 Pa
Answer: The pressure exerted by the weight on the surface is 250 Pa.