Explore topic-wise InterviewSolutions in Current Affairs.

If \(\vec{F_1},\vec{F_2},\vec{F_3}\),…….. are the concurrent forces acting at the same point, then the point will be in equilibrium if

\(\vec{F_1}+\vec{F_2}+\vec{F_3}\) +………= \(\vec{0}\)

A body on a circular path has two kinds of accelerations: radial & linear

1. If speed is constant linear acceleration is zero & radical acceleration is ar = \(\frac {v^2}{r}\)

v = 40ms^-2

r = 400 m 

⇒ ar = \(\frac {40 \times 40}{400}\) = 4ms^-2

2. If the speed increases at 3 m/s², it has a linear acceleration of 3ms^-2.

a = \(\sqrt {a_r^2+a_1^2}\)

= \(\sqrt {3^2+4^2}\)

= 5 ms^-2.

Speed of the plane = 360 km/hr

= \(\frac {360 \times 10^3}{3600}\) = 100 ms^-1

we know that tan θ = \(\frac {v^2}{rg}\)

⇒ r = \(\frac {v^2}{tan \,\theta \times g}\) = \(\frac {100 \times 100}{tan(20°)\times 10}\)

= 2.747 km.

Correct option is: (a) may not be zero

Dimensional equations are used :

1. To check the correctness of an equation.

2. To derive the relation between different physical quantities.

3. To convert one system of units into another system.

Uses of dimensional equations: 

(i) To convert a physical quantity from one system of units to another. Suppose a physical quantity has dimensional formula M ^aL^bbT^c and n₂ be its numerical values when the units are u₁ and u₂. Then n₁ u₁ = n₂ u₂ 

(ii) To check the corrections of a given physical relation. 

(iii) To derive a relationship between different physical quantities.

The significant figures are normally those digits in a measured quantity which are known reliably plus one additional digit that is uncertain. 

1. When one marble is hit by another marble, both the marbles move with some velocity. 

2. When the marble is hit by two, three marbles, all marbles move with a velocity which is more than in the previous case.

3. As we are hitting with more marbles, the mass increases. So that the net momentum also increases.

Rules for counting the number of significant figures in a measured quantity: 

(i) All non-zero digits are significant. 

(ii) All zeros between two-non zero digits are significant. 

(iii) All zeros to the right of a non-zero digit but to left of an understood decimal point are not significant. But such zeros are significant if they come from a measurement. 

(iv) All zeros to the right of a non-zero digit but to left of a decimal point are significant. For example, 648700 has a significant figures. 

(v) All zeros to the right of a decimal point are significant. 

(vi) All zeros to the right of a decimal point but to the left of a nonzero digit are not significant. Single zero conventionally placed to the left of the decimal point is not significant. 

(vii) The number of significant figures does not depend on the system of units.

Correct option is D) 15 m/s²

Mass m = 30 kg. ; Force F = 450 N Acceleration a = ? 

F = ma 

∴ a = \(\frac{F}{m}=\frac{450}{30}\) =15 m/sec² 

∴ The required acceleration =15 m/sec²

The answer is (c) \(-2\sqrt2\)

B) Second law of motion

Correct option is C) impulse

Correct option is D) impulse

Correct option is D) impulse

If the proportion of fine particles is more the soil is clay.

Orchard: A collection of fruit trees.

Social forestry could help overcome deforestation.

People usually live in places in the forest where water is available.

Forests are an important source of timber, fuelwood, cane, resins, lac, oils, fruits, nuts, honey, etc.

People living in forests depend on its products for their livelihood.

Tribe: A group of people, often of related families, who live together, sharing the same languages, culture, and history.

Forest helps in binding soil and protecting it from erosion.

Forests serve as the lungs of our earth.

• Forests provide habitat to wild life.
• Forests help in causing rain.
• They keep the surroundings clean.

Crop rotation: a plant cultivated on a large scale for its produce.

Loamy: a medium-textured soil containing a mixture of large and small mineral particles. (rich soil)

Clay: a type of soil that can be easy to roll into a ball or ring and not cracked

Removal of topsoil by wind, water, or any other means is known as soil erosion.

Clay, loam, and sand are types of soil.

The amount of water that passes through gives us a percolation rate. It is highest in the sandy soil and least in the clayey soil.

During heavy winds, we observe that the surface soil particles are carried away by air. It is very important to preserve the fertility of the soil.

Soil is formed slowly as rock erodes into tiny pieces near the earth’s surface.

If large and fine particles are present in equal proportions, the soil is called loam.

If the proportion of large-sized particles is more, we call the soil sandy.

We depend on soil for agriculture, construction purposes, making utensils, toys, etc Making pots by using soil is called pottery.

Water passing down through the soil particles is called percolation.

• The soil supports all plants, animals, and microorganisms.
• Almost all the things in our surroundings directly or indirectly depend on soil.

Correct option is (C) 13 cm

Slant height of cone is \(l=\sqrt{r^2+h^2}\)

\(=\sqrt{5^2+12^2}=\sqrt{25+144}\)

\(=\sqrt{169}\) = 13 cm

Correct option is  C) 13 cm

Correct option is (D) πrl

Curved surface area of a cone \(=\pi rl\)

Correct option is  D) πrl

Correct option is (D) 44 cm²

\(r=\frac d2=\frac72\,cm\) and \(l\) = 4 cm

\(\therefore\) Curved surface area of cone \(=\pi rl\)

\(=\frac{22}7\times\frac72\times4=11\times4\)

\(=44\,cm^2\)

Correct option is  D) 44 cm²

Correct option is: (B) Bulk modulus

The stress at which the specimen breaks or ruptures ultimately is called ultimate or tensile strength.

1. When a balloon is filled with air at high pressure, its walls experience a force from within. It tries to expand the balloon and change its size without changing shape. When the volume stress exceeds the limit of bulk elasticity, the balloon explodes.

2. A gas cylinder explodes when the pressure inside it exceeds the limit of bulk elasticity of its material.

3. A submarine when submerged under water is under volume stress. The depth it can reach within water depends upon its limit of bulk elasticity.

Elasticity is reciprocal of compressibility. Air is more compressive than water. Hence water is more elastic than air.

Louis Pasteur established theory of biogenesis.

Oil immersion is a technique used to increase the resolution of a microscope.

Tube light: A lamp that produces visible light by fluorescence, especially a glass tube whose inner wall is coated with a material that fluoresces when an electrical current causes a vapor within the tube to discharge electrons.

Bulbs in series: A number of bulbs arranged or coming one after the other in succession.