Physics Test 158

Result

Physics Test 158

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
4 / -1

The venturi-meter works on:

A
Bernoulli's principle

B
The principle of parallel axes

C
The principle of perpendicular axes

D
Huygen's principle

Solution

A venturi meter is a device used to measure the flow rate of a fluid through a pipe. The venturi meter works on Bernoulli's principle, which states that for an incompressible, non-viscous fluid flowing through a pipe, the sum of the pressure energy, kinetic energy, and potential energy per unit volume remains constant.
Question 2
4 / -1

An open-ended U-tube of uniform cross-sectional area contains water (density 1.0 gram/centimeter³) standing initially 20 centimeters from the bottom in each arm. An immiscible liquid of density 4.0 grams/centimeter³ is added to one arm until a layer 5 centimeters high forms, as shown in the figure above. What is the ratio h₂/h₁ of the heights of the liquid in the two arms ?

A
3/1

B
5/2

C
2/1

D
3/2

Solution

5 × 4 × 10 + (h₁ - 5) × 10 = h₂ × 1 × 10

200 + 10h₁ – 50 = 10h₂

10h₂ - 10h₁ = 150

h₂ - h₁ = 15

h₂ + h₁ = 20 + 20 + 5 = 45

2h₂ = 60

h₂ = 30

h₁ = 15

h₂/h₁ = 30/15

h₂/h₁ = 2/1
Question 3
4 / -1

A fluid container is containing a liquid of density r is is accelerating upward with acceleration a along the inclined place of inclination a as shwon. Then the angle of inclination q of free surface is :

A

B

C

D

Solution

First resolve all components in the along and perpendicular to incline. Pressure difference is created in a vertical column full of liquid. This is because of gravity acting in downward direction. Similarly, pressure difference will be created too along the incline. So, p = h * d * g * cosa (in perpendicular direction) and

p = hd (a + g sina) (along incline).

So, tan(theta) = (a + gsina)/(gcosa)
Question 4
4 / -1

Figure shows a three arm tube in which a liquid is filled upto levels of height l. It is now rotated at an angular frequency w about an axis passing through arm B. The angular frequency w at which level of liquid of arm B becomes zero.

A

B

C

D

Solution
Question 5
4 / -1

A metal ball of density 7800 kg/m³ is suspected to have a large number of cavities. It weighs 9.8 kg when weighed directly on a balance and 1.5 kg less when immersed in water. The fraction by volume of the cavities in the metal ball is approximately :

A
20%

B
30%

C
16%

D
11%

Solution

Here when put in water the water displaces/fills the empty cavity.

Volume of only metal = mass/density = 9.8/7800 = 1.25X10^-3 cubic m

Volume of whole ball including cavity = weight of water displaced/density of water

Density of water is 1000 kg/cubic m.

Volume of whole ball = 1.5X10^-3 cubic m

Volume of cavity = Volume of ball - volume of metal

= 1.5X10^-3 - 1.25X10^-3

= 0.25X10^-3 cubic m

Ratio of volume of cavity/ball = 0.25X10^-3 / 1.5X10^-3 = 0.16 = 16%

0.16 fraction of whole ball is a cavity i.e. 16%
Question 6
4 / -1

A rectangular tank is placed on a horizontal ground and is filled with water to a height H above the base. A small hole is made on one vertical side at a depth D below the level of the water in the tank. The distance x from the bottom of the tank at which the water jet from the tank will hit the ground is

A

B

C

D

Solution

Time taken by liquid drop to fall

S=ut+(1/2)at²

t=√2(H−D)/g

Horizontal velocity of liquid =√2gD

Range =√2(H−D)/g× √2gD

Range =2√D(H−D)
Question 7
4 / -1

A cylindrical block of area of cross-section A and of material of density r is placed in a liquid of density one-third of density of block. The block compresses a spring and compression in the spring is one-third of the length of the block. If acceleration due to gravity is g, the spring constant of the spring is

A
rAg

B
2rAg

C
2rAg/3

D
rAg/3

Solution

Since the block is at rest, net force on the cylinderical block is zero, ie net upward = net downward force
Question 8
4 / -1

A sphere of radius R and made of material of relative density s has a concentric cavity of radius r. It just floats when placed in a tank full of water. The value of the ratio R/r will be

A

B

C

D

Solution

If the sphere is "just" floating means the sphere is exactly immersed in water (or) the buoyant force acting on it is exactly equal to its weight. The cavity reduces the weight of the actual sphere but has no role in the buoyant force.
Question 9
4 / -1

Two copper vessels A and B have the same base area but of different shapes. A takes twice the volume of water as that B requires to fill upto a particular common height. Then the correct statement among the following is:

A
Vessel B weighs twice that of A.

B
Pressure on the base area of vessels A and B is same

C
Pressure on the base area of vessels A and B is not same

D
Both vessels A and B weigh the same

Solution

In hydrostatic condition,

P = P₀+ ρgh

Here, P : absolute pressure at depth h, P₀ is atmospheric pressure

Since, height of liquid in both vessel is same therefore pressure on the base of both vessel will be same.
Question 10
4 / -1

Let a wire be suspended from the ceiling (rigid support) and stretched by a weight W attached at its free end. The longitudinal stress at any point of cross-sectional area A of the wire is:

A
W/A

B
W/2A

C
Zero

D
2W/A

Solution

When a wire is suspended from the ceiling and stretched by a weight W attached at its free end, the force acting on the wire is equal to the weight W. This force causes longitudinal stress in the wire.

Longitudinal stress is defined as the force acting on an object divided by its cross-sectional area. In this case, the force acting on the wire is W, and the cross-sectional area of the wire is A.

Thus, the longitudinal stress at any point of the wire with cross-sectional area A is given by: