Archimedes' Principle

Q.

Why a block of plastic when released under water come up to the surface of water?

Q.

The centre of _________ is a point, where the total upthrust, due to fluid displaced by _________ part of body acts.

Q.

When a stone is immersed in water it displaces water of weight 5 N, calculate the upthrust acting on the stone.

Q.

NAME THE FOLLOWING:

The principle which gives the magnitude of buoyant force acting on an object immersed in a liquid.

Q. An airtight box, having a lid of area 50 cm² is partially evacuated. Atmospheric pressure is 1.01 × 10⁵ Pa. To open the lid, net outward force should be equal to net inward force. If a minimum force of 500 N is required to pull the lid off the box. The pressure in the box was

50 cm² क्षेत्रफल के ढक्कन वाले एक वायुरोधी बक्से को आंशिक रूप से निर्वातित किया जाता है। वायुमण्डलीय दाब 1.01 × 10⁵ Pa है। ढक्कन को खोलने के लिए नेट बाह्य बल, नेट आन्तरिक बल के बराबर होना चाहिए। यदि बक्से के ढक्कन को ऊपर खींचने के लिए 500 N के न्यूनतम बल की आवश्यकता होती है, तब बक्से में दाब था

1. 2.04 × 10⁵ Pa
2. 10³ Pa
3. 10⁴ Pa
4. 1.1 × 10⁵ Pa

Q.

In the case of a floating body, the weight of the whole body is equal to the weight of the fluid displaced by its immersed part. The statement is called _________.

Q.

State the relationship between the buoyant force on an object and the weight of the liquid displaced by it?

Q.

A manometer uses the principle of buoyancy.

1. True
2. False

Q. Two blocks A and B of cubical shapes weighing 80 N and 40 N and sides of length 4 cm and 1 cm respectively are placed on a table as shown in figure. The pressure experienced by the table due to blocks is

घनाकार आकृत्तियों के दो गुटकों A तथा B के भार 80 N तथा 40 N हैं तथा इनकी भुजा लम्बाई क्रमशः 4 cm तथा 1 cm हैं, इन्हें चित्र में दर्शाए अनुसार एक मेज पर रखा गया है। गुटकों के कारण मेज द्वारा अनुभव किया गया दाब है

1. 1.25 × 10⁴ N/m²
   
2. 7.5 × 10⁵ N/m²
   
3. 7.5 × 10⁴ N/m²
   
4. 6.25 × 10² N/m²
   

Q.

State the law of flotation.

Q. A body floats in a liquid with a part of it submerged inside liquid. What is the apparent weight of the floating body?

1. $0$
2. Equals to its weight
3. Equals to buoyancy force acting on it
4. Can not be determined

Q. According to Archimedes' principle buoyant force is equal to the_______ of the liquid displaced.

1. volume​
2. density​
3. mass​
4. weight​

Q. A solid weighs $120gf$ in air and $105gf$ when it is completely immersed in water. Calculate the relative density of solid.

1. $1/8$
2. $8$
3. $8/7$
4. $7/8$

Q. A solid weighs $1.5kgf$ in air and $0.9kgf$ in a liquid of density $1.2\times {10}^{3}kg{m}^{-3}$. Calculate relative density of solid.

1. $\frac{2}{4}$
2. $\frac{1}{3}$
3. $3$
4. $\frac{1}{4}$

Q. A metallic sphere floats in immiscible mixture of water (density ${10}^{3}kg/m^3$) and a liquid (density $8\times {10}^{3}kg/m^3$) such that its $\left(2/3\right)$ part is in water and $\left(1/3\right)$ part in the liquid. The density of the metal is

1. $\frac{5000}{3}kg/m^3$
2. $\frac{10000}{3}kg/m^3$
3. $5000kg/m^3$
4. $2000kg/m^3$

Q. What is buoyancy?

Q. A boat full of scrap iron is floating on water in a lake. If all the iron is dropped into the water, the level of water will:

1. go up
2. fall down
3. remain the same
4. Can not be decided.

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Explain why an iron needle sinks in water, but a ship made of iron floats on water.

Q. An object weighs $30N$. It displaces a volume of water that weighs $25N$.
(i) what is the buoyant force on the object?
(ii) will this object float or sink? Explain your answer.

Q. Two vessels A and B of different shapes have the same base area and are filled with water up to the same height h (see figure). The force exerted by water on the base is $F_A$ for vessel A and $F_B$ for vessel B. The respective weights of the water filled in vessels are $W_A$ and $W_B$. Then

1. $F_A>F_B;W_A>W_B$
2. $F_A=F_B;W_A>W_B$
3. $F_A=F_B;W_A<W_B$
4. $F_A>F_B;W_A=W_B$

Q.

A wooden block floats in water with one-fourth of its volume immersed, the density of wood will be:

Q. A ball of steel whose volume is $100\text{cc}$ was thrown into a vessel filled with water upto its brim. Assuming the vessel is cylindrical with a height of $30\text{cm}$ and a base radius of $5\text{cm}$, find the volume of water displaced, the buoyant force on the ball and reduction in the height of water column in the vessel after the ball is removed. (Relative density of steel is $7.7$)

1. $100\text{cc},1\text{N},1.27\text{cm}$
2. $100\text{cc},0.1\text{N},28.73\text{cm}$
3. $100{\text{m}}^3,10\text{N},1.27\text{cm}$
4. $100{\text{m}}^3,1\text{N},28.73\text{cm}$

Q. On what principle does Lactometer work?

1. Newton's law of motion
2. Pascal's law
3. Archimedes' principle
4. Law of gravitation

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Distinguish between density and relative density.

Q. According to Archimedes' Principle buoyant force is equal to the _ of the liquid displaced.

1. Volume
2. Density
3. Weight
4. Mass

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Distinguish between density and relative density.

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Explain why an iron needle sinks in water, but a ship made of iron floats on water.

Q. A piece of stone weighing 200 g when immersed in water taken in a Eureka can displaces 20 mL of water. Find the density of the stone in kg $m^{-3}$.

1. 2000 kg $m^{-3}$
2. 20, 000 kg $m^{-3}$
3. 10, 000 kg $m^{-3}$
4. 1000 kg $m^{-3}$