**AP 9th Class Physical Science Chapter 8 Solution – Floating Bodies**

Andhra Pradesh SCERT 9th Class Physical Science Chapter 8 **Floating Bodies** Solution for AP 9th Class Physics/Chemistry Exam. Lots of Students of Andhra Pradesh Board will search on internet for Andhra Pradesh Class 9 **Physical Science Textbook Solution or Study Material for **AP 9th exam. Here you search will end! Here in this page we have provided for all question answer for AP SCERT **Chapter 8 Floating Bodies**.

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**AP 9th Class Chemistry Chapter 8 Floating Bodies Solution**

**1) A solid sphere has a radius of 2 cm and a mass of 0.05 kg. What is the relative density of the sphere? (AS1)**

**Ans: – **Mass = 0.05kg or 50g.

As we all know density= mass/ volume= 50/ (4/3×πr^3) =50/ (4/3×π×2^3) = 1.49 g/cm^3.

So the relative density of the sphere is (sphere density/water density) =1.49/1=1.49.

**2) A small bottle weighs 20 g when empty and 22 g when filled with water. When it is filled with oil it weighs 21.76 g. What is the density of oil? (AS1)**

**Ans: –**Weight of water is = filled with water – weight of the bottle= (22-20) =2g.

So the volume of the water = mass/density= 2/1=2 g/cm^3.

Then the density of the oil = mass of the oil / volume of the bottle = (21.76-20)/2=0.88 g/cm3.

**3) An ice cube floats on the surface of a glass of water (density of ice =0.9 g/cm3).Whenthe ice melts will the water level in the glass rise? (AS1)**

**Ans: – **The water level in the glass would not change. The mass of both the ice and water are same only volume is different so there will be no change in water level when ice melts.

**4) The volume of 50g of a substance is 20 cm3. If the density of water is 1g/cm3, will the substance sink or float when placed on the surface of water? What will be the mass of water displaced by the substance? (AS1)**

**Ans: –**The density of the substance = mass / volume = 50/20 = 2.5gcm^-3.

The density of the substance is 2.5 which is more than water, so the substance will float on water according to Archimedes principal.

The amount of water which will be displaced is 20× 1(d=m/v) =20 g.

**5) Find the pressure at a depth of 10m in water if the atmospheric pressure is 100kPa.[1Pa=1N/m2] [100kPa = 105Pa = 105N/m2 = 1 atm.]**

**Ans: – **As we know the pressure=pgh, where p is density, g is gravitational constant, h is height. Density of water is 1 g/cm^3 or 1000k/m^3.

Pressure at a depth of 10m is = atmospheric pressure + pressure at bottom = 100kpa + pgh = (10^5 + 1000×10×10) N/m^2 = 2.0×10^5 N/m^2= 200kpa.

**6) Why some objects float on the water? And some sink? (AS1)**

**Ans: –**According to Archimedes principal which substance has more density than water will sink and which has less density as compared to water willfloat on water.

**7) Explain density and relative density and write formulae. (AS1)**

**Ans: – **Density is the ratio of mass and volume of a substance.

Density (D) = mass (m)/ volume (v).

The relative density is the ratio of density of a substance to water.

Relative density = density of substance/ density of water.

**8) What is the value of density of water? (AS1)**

**Ans: – **The density of water is 1 g/ml or 1000k/m^3.

**9) Find the relative density of wood. Explain the process. (AS3)**

**Ans: – **For calculation of relative density of wood measure the weight of the wood when in air (w1) and measure the weight of wood when it in water (w2). Then the relative density of the wood will be according to Archimedes principle is

(Weight of wood in air / apparent weight of woo) = (w1 / w1 -w2).

**10) Which is denser, water or milk? (AS2)**

**Ans: – **Milk is denser compared to water.

**11) What is buoyancy? (AS1)**

**Ans: –**Buoyancy is the upper thrust force which felt by any object when immersed in water or liquid. According to Archimedes principal when an object is kept in water the equal amount of volume of sink part of the object as water displaced.

**12) Classify the following things into substances having Relative Density> 1 and Relative Density< 1 Wood, iron, rubber, plastic, glass, stone, cork, air, coal, ice, wax, paper,milk, kerosene, groundnut oil, soap (AS1)**

**Ans: –**The substance which has relative density greater than 1 is iron, glass, stone, coal, milk, paper.

The substance which has relative density less than 1 is wood, rubber, plastic, cork, air, wax, groundnut oil, soap.

**13) How can you appreciate the technology of making ships float, using the material which sink in water? (AS6)**

**Ans: – **Th**e** technology which is used to make ships flow over water to get maximum buoyancy force. It should follow that there must be maximum pressure will apply to the base of the ships which float on the water.

**14) Can you make iron to float? How? (AS3)**

**Ans:-. **Floating of iron on water ispossible as the amount of water which displaced by the iron shape should be equal or more than the weight of the weight of the iron. By this principal large iron ships are made.

**15) How can you find the relative density of a liquid? (AS3)**

**Ans: – **The relative density of any liquid is the ratio of weight of the liquid to the volume of the same water.

Relative density = (liquid weight/water volume).

**16) Find the relative density of different fruits and vegetables and write a list. (AS3)**

**Ans: –**The relative density of different fruit is – apple-1.04, lemon -1.02, water melon-0.94, onion-0.92 etc.

**17) Make a lactometer with refill. What you do to make the refill stand vertically straight?**

**Ans: –**After taking a refill with a metallic point in it one side place into some part of it in a water boiling tube and mark the point from which it is in air and take reading. Use rubber to stand the refill in the tube. And after that add milk into the tube and take reading from the mark up point of the refill. Continue these process by changing the volume of water mixture and milk then comparing the value you will able to find the purity of milk.

**18) Draw the diagram of mercury barometer. (AS5)**

**Ans:-**

**19) How do you appreciate Pascal’s discovery in helping to make hydraulic jacks. (AS6)**

**Ans: – **As the whole working principal of hydraulic jacks is base on the Pascal’s law so it has huge impact on them. As we came to know from the Pascal’s law that if we create some pressure on any point of the liquid this pressure divided equally to every point. In hydraulic jack there also liquid present in it creates same pressure to each point.

**20) How do you appreciate Archimedes discovery of force of buoyancy. (AS6)**

**Ans: – **Buoyancy is the upper thrust force exert by the liquid to shape of any material which is immerse in water. According to Archimedes principal equal amount of water is displaced by any object that how much part of it is sink in water so upper thrust is given by water to displaced the water.

**21) You found the relative densities of some solids and some liquids by some activities. List the solids and liquids in increasing order of relative density.(AS4)**

**Ans: – **The relative density of some solid in increasing order are wood (0.2), paraffin (0.96), aluminium (2.72), and iron (7.2).

The increasing order of some liquid is kerosene (0.8), diesel (0.82), coconut (0.92), and milk (1.02).

**22) Iron sinks in water, wood floats in water. If we tied an iron piece to the same volume of wood piece, and dropped them in water, will it sink or float? Make a guess and find out whether your guess is correct or wrong with an experiment. Give reasons. (AS2. (AS3)**

**Ans:-. **According to Archimedes principal a substance will float on water when the weight of the substance is smaller that the water displaced by it. So when we sink iron this principal doesn’t follow and it doesn’t float on water. But in combined case this upper condition is followed and these combination of iron and wood float on water.

**23) Liquid brakes in automobiles follow principle of brahma press (Pascal’s principle). What about air brakes? Collect the information about the working process of air brakes.(AS4)**

**Ans: – **The components in air break are compressor, storage tank, main control device, break chamber, drum break. The compressor store the air in the storage tank, which exert pressure to the engine. The main control device then change break intensity by regulating the air pressure. The break chamber convert air pressure to mechanical force by which drum break creates friction to stop the wheels.

**24) Where do you observe Archimedes principle in our daily life? Give two examples.(AS7)**

**Ans: – **The daily life example of Archimedes principal is– the floating of mug in water, plastic ship floats on water, air balls float in swimming pool etc.

**25) Where do you observe Pascal’s principle in our daily life? Give few examples.(AS7)**

**Ans: –**The daily life example of Pascal’s law is – shower in the bathroom, hydraulic lift, hydraulic jack, hydraulic breaks etc.