**Pressure in Fluids and Atmospheric Pressure Exe-4B** **Atmospheric Pressure and it’s Measurement Numericals Answer** Type for Class-9 ICSE Concise Physics. There is the solutions of **Numericals Answer** type Questions of your latest textbook which is applicable in 2023-24 academic session**. **Visit official Website CISCE for detail information about ICSE Board Class-9.

**Pressure in Fluids Exe-4B Atmospheric Pressure and it’s Measurement Numericals Answer **

**(ICSE Class – 9 Physics Concise Selina Publishers)**

Board | ICSE |

Class | 9th |

Subject | Physics |

Writer / Publication | Concise selina Publishers |

Chapter-4 | Pressure in Fluids and Atmospheric Pressure |

Exe – 4B | Atmospheric Pressure and it’s Measurement |

Topics | Solution of Exe-4(B) Numericals Answer Type |

Academic Session | 2023-2024 |

**Exe-4B Atmospheric Pressure and it’s Measurement Numericals Answer Type**

**Ch-4 Pressure in Fluids and Atmospheric Pressure Physics Class-9 ICSE Concise**

**Page 113**

**Question 1. **Convert 1 mm of Hg into pascal. Take density of Hg = 13.6 x 10^{3} kg m^{-3} and g = 9.8 m s^{-2} .

**Answer:**

We know that, the pressure is given by the formula,

δP = hρg

Putting the given values in above equation, we get,

δP = 0.001 x 13.6 x 1000 x 9.8

δP = 133.28 Pa

Therefore, 1 mm of Hg is equal to 133.28 pascals.

**Question 2. **At a given place, a mercury barometer records a pressure of 0.70 m of Hg. What would be the height of water column if mercury in barometer is replaced by water? Take density of mercury to be = 13.6 x 10^{3}

**Answer:**

Relative Density of Hg = 1.36 = kgm 13.6 × 10^{3} kgm^{-3}

Acceleration due to gravity , g = 9.8 msms^{-2}

Height of mercury column = 0.70 m

∴ Pressure , P = hρg

or , P = (0.7)(1.36 × 10^{3})(9.8) pascal

or , P = 93.3 × 10^{3} Pa

Let h be the height of water column

Then , P = h (density of water) g

or , 93.3× 10^{3} = h × 10^{3 }×9.8

**or , h = 9.52 m**

**Question 3. **At sea level, the atmospheric pressure is 76 cm of Hg. If air pressure falls by 10 mm of Hg per 120m of ascent, what is the height of a hill where the barometer reads 70 cm Hg. State the assumption made by you.

**Answer:**

Atmospheric pressure , P = 76 cm Hg

Rate at which pressure falls = 10 mm of Hg per 120 m of ascent = 1 cm of Hg per 120 m of ascent

Let h be the height of the hill.

Pressure at hill , P’ = 70 cm Hg

Total fall in pressure = P – P’ = (76 – 70) cm Hg = 6 cm Hg

Now , fall in pressure is 1 cm Hg for every 120 m increase in height

Thus , if the fall in pressure is 6 cm Hg , increase in height shall be (6 × 120)m = 720 m

∴ Height of the hill = 720 m

Assumption: Atmospheric pressure falls linearly with ascent.

**(Pressure in Fluids and Atmospheric Pressure Exe-4B Numericals Class-9 ICSE)**

**Question 4. **At sea level, the atmospheric pressure is 1.04 x 10^{5} Pa. Assuming g = 10 m s^{-2} and density of air to be uniform and equal to 1.3 kg m^{-3}, find the height of the atmosphere.

**Answer:**

Pressure = hdg

h = Pressure / (dg)

= (1.04 × 10^{5} Pa) / (1.3 kg/m³ × 10 m/s²)

= 8000 m

= 8 kilometers

Height of the atmosphere is 8 kilometers

**Question 5. **Assuming the density of air to be 1.295 kg m^{-3}, find the fall in barometric height in mm of Hg at a height of 107 m above the sea level. Take density of mercury = 13.6 × 10^{3} kg m^{-3}.

**Answer:**

— : End of **Pressure in Fluids and Atmospheric Pressure** Exe-4B **Numericals Answer** Type Solutions :–

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