Question

A 50 cm tall glass is filled with water to a depth of 40 cm .
a. what is the gauge pressure at the bottom of the glass ?
b. what is the absolute pressure at the bottom of the glass ?​

Answer 1

Answer:

Practice Problems Worksheet Answer Key

Show complete solutions to the following problems and box final answers with units.

1. A sample of an unknown material weighs 300 N in air and 200 N when submerged in an alcohol

solution with a density of 0.70 x 103

kg/m3

. What is the density of the material?

Given:

Fg(air) = 300 N

Fg(alcohol) = 200 N

ρalcohol = 0.7 x 103

kg/m3

Unknown:

ρmaterial or ρo

Solution:

FB = Fg(air) – Fg(alcohol) = 300 N – 200N

FB = 100 N

Fg(air) / FB = ρo / ρalcohol

ρo = Fg(air) / FB * ρalcohol = (300 N / 100 N) * 0.7 x 103

kg/m3

ρo = 2.1 x 103

kg/m3

2. A 40-cm tall glass is filled with water to a depth of 30 cm.

a. What is the gauge pressure at the bottom of the glass?

b. What is the absolute pressure at the bottom of the glass?

Given:

h = 30 cm = 0.3 m

g = 9.81 m/s2

ρwater = 1.0 x 103

kg/m3

Uknown:

a) Pgauge

b) Pabsolute

Solution:

a) Pgauge = ρgh = (1.0 x 103

kg/m3

) (9.81 m/s2

) (0.3 m)

Pgauge = 2.9 x 103

kg/m3 Pa

b) Pabsolute = Patm + Pgauge

Pabsolute = 1.01 x 105 Pa + 2.9 x 103

kg/m3 Pa

Pabsolute = 1.04 x 105 P

Answer 2

Concept:

• Pressure
• Gauge and absolute pressures

Given:

• The depth of water h = 40cm = 0.4 m
• Acceleration due to gravity g = 9.8 m/s^2
• The density d of water = 10^3 kg/m^3

Find:

• The gauge pressure at the bottom of the glass
• The absolute pressure at the bottom of the glass

Solution:

Gauge pressure = dgh

Gauge pressure = (10^3 kg/m^3)  (0.4 m) (9.8 m/s^2)

Gauge pressure = 3920 Pa

Absolute pressure = gauge pressure + atmospheric pressure

atmospheric pressure = 1.01 *10^5 Pa

Absolute pressure =  3920 Pa + 1.01 *10^5 Pa

Absolute pressure =  104920 Pa

The gauge pressure is 3920 Pa and the absolute pressure is 104920 Pa.

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