PAF Physics Academic Test

A body of mass 2 kg is dropped from a height of 10m. Kinetic energy just before hitting the ground is ($g=10$):

1 Mark(s)

Your Answer:

$200 J$ $200 J$
$100 J$ $100 J$
$400 J$ $400 J$
$50 J$ $50 J$

The direction of the angular velocity vector is given by:

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Your Answer:

Right Hand Rule Right Hand Rule
Left Hand Rule Left Hand Rule
Vector Addition Vector Addition
Scalar Product Scalar Product

Three vectors satisfy $\vec{A} + \vec{B} + \vec{C} = 0$. If magnitudes are 3, 4, 5, then angle between $\vec{A}$ and $\vec{B}$ is:

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Your Answer:

$0^\circ$ $0^\circ$
$90^\circ$ $90^\circ$
$60^\circ$ $60^\circ$
$120^\circ$ $120^\circ$

Snell's Law is related to:

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Your Answer:

Reflection Reflection
Refraction Refraction
Absorption Absorption
Transmission Transmission

The angle of contact for pure water and clean glass is approximately:

1 Mark(s)

Your Answer:

$0^\circ$ $0^\circ$
$90^\circ$ $90^\circ$
$135^\circ$ $135^\circ$
$180^\circ$ $180^\circ$

Viscosity of liquids ______ with rise in temperature.

1 Mark(s)

Your Answer:

Increases Increases
Decreases Decreases
Remains same Remains same
Becomes zero Becomes zero

Which branch of Physics deals with the study of motion of material objects?

1 Mark(s)

Your Answer:

Mechanics Mechanics
Thermodynamics Thermodynamics
Optics Optics
Electrodynamics Electrodynamics

The power of a water pump is 2 kW. If $g=10 m/s^2$, the amount of water it can raise in 1 minute to a height of 10 m is:

1 Mark(s)

Your Answer:

100 liters 100 liters
2000 liters 2000 liters
1200 liters 1200 liters
1000 liters 1000 liters

Planets revolve around the Sun in:

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Your Answer:

Circular orbits Circular orbits
Elliptical orbits Elliptical orbits
Parabolic paths Parabolic paths
Hyperbolic paths Hyperbolic paths

Which mode of heat transfer does not require a material medium?

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Your Answer:

Conduction Conduction
Convection Convection
Radiation Radiation
Advection Advection

The bending of light when it passes from one medium to another is called:

1 Mark(s)

Your Answer:

Reflection Reflection
Dispersion Dispersion
Refraction Refraction
Diffraction Diffraction

Which of the following does not support the wave theory of light?

1 Mark(s)

Your Answer:

Interference Interference
Diffraction Diffraction
Photoelectric Effect Photoelectric Effect
Polarization Polarization

A composite wire of length $2L$ is made by joining two wires A and B of same material, length $L$ and radii $2r$ and $r$. A force $F$ is applied. The ratio of potential energy stored in A to B is:

1 Mark(s)

Your Answer:

01:02:00 01:02:00
04:01:00 04:01:00
01:04:00 01:04:00
01:01:00 01:01:00

Which of the following is a unitless quantity?

1 Mark(s)

Your Answer:

Force Force
Stress Stress
Velocity Velocity
Strain Strain

The breaking force of a wire of radius $r$ is $F$. The breaking force of a wire of same material and radius $2r$ will be:

1 Mark(s)

Your Answer:

$F$ $F$
$2F$ $2F$
$F/4$ $F/4$
$4F$ $4F$

Which of the following is correct regarding 'Random Errors'?

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Your Answer:

They are always positive They are always positive
They can be minimized by averaging They can be minimized by averaging
They are due to instrument zero error They are due to instrument zero error
They follow a linear pattern They follow a linear pattern

A sphere of solid material of specific gravity 8 has a concentric spherical cavity and just floats in water. The ratio of radius of cavity to outer radius is:

1 Mark(s)

Your Answer:

$1/2$ $1/2$
$3/4$ $3/4$
$(7/8)^{1/3}$ $(7/8)^{1/3}$
$(5/8)^{1/3}$ $(5/8)^{1/3}$

Work done is a:

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Your Answer:

Vector quantity Vector quantity
Scalar quantity Scalar quantity
Tensor quantity Tensor quantity
Undefined Undefined

The work done by the gravitational force on a body moving in a closed path is:

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Your Answer:

Zero Zero
Positive Positive
Negative Negative
Depends on path Depends on path

The SI unit of Frequency is:

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Your Answer:

Second Second
Hertz Hertz
Meter Meter
Joule Joule

The pressure at the bottom of a water tank is $4P$ where $P$ is atmospheric pressure. The height of water is approximately ($P = 10^5 Pa, g=10$):

1 Mark(s)

Your Answer:

10 m 10 m
20 m 20 m
30 m 30 m
40 m 40 m

Calculate the area of a sheet of length 2.1 m and width 1.2 m to correct significant figures.

1 Mark(s)

Your Answer:

2.52 $m^2$ 2.52 $m^2$
2.5 $m^2$ 2.5 $m^2$
2.6 $m^2$ 2.6 $m^2$
3 $m^2$ 3 $m^2$

A body of mass $m$ rests on a horizontal floor with coefficient of static friction $\mu$. The minimum force required to move the body is:

1 Mark(s)

Your Answer:

$\mu mg$ $\mu mg$
$mg$ $mg$
$mg \sqrt{1+\mu^2}$ $mg \sqrt{1+\mu^2}$
$\frac{\mu mg}{\sqrt{1+\mu^2}}$ $\frac{\mu mg}{\sqrt{1+\mu^2}}$

Second Law of Thermodynamics implies that heat cannot flow spontaneously from:

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Your Answer:

Hot to Cold Hot to Cold
Cold to Hot Cold to Hot
High pressure to Low pressure High pressure to Low pressure
Vacuum to Air Vacuum to Air

Sound waves with frequency below 20 Hz are called:

1 Mark(s)

Your Answer:

Infrasonic Infrasonic
Ultrasonic Ultrasonic
Audible Audible
Supersonic Supersonic

When a mass is rotating in a plane about a fixed point, its angular momentum is directed along:

1 Mark(s)

Your Answer:

The radius The radius
The tangent to orbit The tangent to orbit
Axis of rotation Axis of rotation
Line at $45^\circ$ to plane Line at $45^\circ$ to plane

The SI unit of 'Luminous Intensity' is:

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Your Answer:

Lumen Lumen
Candela Candela
Lux Lux
Watt Watt

The weight of an object in a free-falling lift is:

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Your Answer:

Zero Zero
$mg$ $mg$
$2mg$ $2mg$
$m(g+a)$ $m(g+a)$

The unit of spring constant $k$ is:

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Your Answer:

$N \cdot m$ $N \cdot m$
$N/m$ $N/m$
$N/m^2$ $N/m^2$
$kg/s$ $kg/s$

The SI unit of Plane Angle is:

1 Mark(s)

Your Answer:

Radian Radian
Steradian Steradian
Degree Degree
Minute Minute

A wheel of moment of inertia $10 kg \cdot m^2$ is rotating at $10 rad/s$. The energy required to stop it is:

1 Mark(s)

Your Answer:

$1000 J$ $1000 J$
$500 J$ $500 J$
$250 J$ $250 J$
$100 J$ $100 J$

The maximum acceleration of a particle in SHM is:

1 Mark(s)

Your Answer:

$\omega A$ $\omega A$
$\omega^2 A^2$ $\omega^2 A^2$
$\omega^2 A$ $\omega^2 A$
$A/\omega$ $A/\omega$

The characteristic of sound that allows us to distinguish between a shrill and a grave sound is:

1 Mark(s)

Your Answer:

Pitch Pitch
Loudness Loudness
Quality Quality
Intensity Intensity

What is the dimensional formula for Speed?

1 Mark(s)

Your Answer:

$[LT^{-1}]$ $[LT^{-1}]$
$[LT^{-2}]$ $[LT^{-2}]$
$[MLT^{-1}]$ $[MLT^{-1}]$
$[L^{-1}T]$ $[L^{-1}T]$

If $\lambda_m$ for a black body at $2000K$ is $\lambda$, then at $3000K$, $\lambda_m$ will be:

1 Mark(s)

Your Answer:

$3\lambda/2$ $3\lambda/2$
$2\lambda/3$ $2\lambda/3$
$\lambda$ $\lambda$
$4\lambda/9$ $4\lambda/9$

A manometer connected to a gas container shows a height difference of 10 cm of Hg. The gauge pressure is:

1 Mark(s)

Your Answer:

10 Pa 10 Pa
10 cm Hg 10 cm Hg
76 cm Hg 76 cm Hg
86 cm Hg 86 cm Hg

Who discovered the law of inertia?

1 Mark(s)

Your Answer:

Isaac Newton Isaac Newton
Galileo Galilei Galileo Galilei
Albert Einstein Albert Einstein
Aristotle Aristotle

A balloon of mass $M$ is descending with constant acceleration $a$. How much mass must be removed to allow it to ascend with same acceleration $a$?

1 Mark(s)

Your Answer:

$\frac{Ma}{g+a}$ $\frac{Ma}{g+a}$
$\frac{2Ma}{g+a}$ $\frac{2Ma}{g+a}$
$\frac{2Ma}{g-a}$ $\frac{2Ma}{g-a}$
$\frac{Ma}{g}$ $\frac{Ma}{g}$

1 Horse Power (hp) is equal to:

1 Mark(s)

Your Answer:

700 Watts 700 Watts
746 Watts 746 Watts
1000 Watts 1000 Watts
500 Watts 500 Watts

Which prefix represents $10^{15}$?

1 Mark(s)

Your Answer:

Tera Tera
Giga Giga
Exa Exa
Peta Peta

The value of Stefan's constant ($\sigma$) is:

1 Mark(s)

Your Answer:

$5.67 \times 10^{-8} W/m^2 K^4$ $5.67 \times 10^{-8} W/m^2 K^4$
$6.67 \times 10^{-11} W/m^2 K^4$ $6.67 \times 10^{-11} W/m^2 K^4$
$3 \times 10^8 W/m^2 K^4$ $3 \times 10^8 W/m^2 K^4$
$1.38 \times 10^{-23} W/m^2 K^4$ $1.38 \times 10^{-23} W/m^2 K^4$

Centripetal force is required for:

1 Mark(s)

Your Answer:

Linear motion Linear motion
Rest Rest
Projectile motion Projectile motion
Circular motion Circular motion

Which of the following is NOT true for a projectile motion?

1 Mark(s)

Your Answer:

Acceleration is constant Acceleration is constant
Path is parabolic Path is parabolic
Velocity is constant Velocity is constant
Total energy is conserved (ideal) Total energy is conserved (ideal)

The ratio of specific heats $C_P / C_V$ for a monoatomic gas is:

1 Mark(s)

Your Answer:

$1.67$ $1.67$
$1.4$ $1.4$
$1.33$ $1.33$
$1$ $1$

Real gases behave like ideal gases at:

1 Mark(s)

Your Answer:

High Pressure, Low Temp High Pressure, Low Temp
High Pressure, High Temp High Pressure, High Temp
Low Pressure, High Temp Low Pressure, High Temp
Low Pressure, Low Temp Low Pressure, Low Temp

The correctness of a physical equation is checked by:

1 Mark(s)

Your Answer:

Principle of Relativity Principle of Relativity
Conservation of Energy Conservation of Energy
Principle of Homogeneity Principle of Homogeneity
Newton's Laws Newton's Laws

Optical fibers work on the principle of:

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Your Answer:

Refraction Refraction
Total Internal Reflection Total Internal Reflection
Diffraction Diffraction
Interference Interference

A 'Light Year' is a unit of:

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Your Answer:

Time Time
Distance Distance
Speed of Light Speed of Light
Intensity of Light Intensity of Light

A body is in equilibrium if:

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Your Answer:

It is moving with constant acceleration It is moving with constant acceleration
It is at rest only It is at rest only
The net external force is zero The net external force is zero
Momentum is changing Momentum is changing

If $x = a e^{-\alpha t} + b e^{\beta t}$, the velocity:

1 Mark(s)

Your Answer:

Drops to zero Drops to zero
Increases with time Increases with time
Decreases with time Decreases with time
Is constant Is constant

A spring has length $L$. If cut into two equal halves, the spring constant of each half becomes:

1 Mark(s)

Your Answer:

$k$ $k$
$2k$ $2k$
$k/2$ $k/2$
$4k$ $4k$

Two spheres of masses $m$ and $M$ are in air. If they are immersed in water, the gravitational force between them:

1 Mark(s)

Your Answer:

Increases Increases
Decreases Decreases
Remains constant Remains constant
Becomes zero Becomes zero

Which physical quantity has the unit 'Steradian'?

1 Mark(s)

Your Answer:

Plane Angle Plane Angle
Luminous Flux Luminous Flux
Solid Angle Solid Angle
Luminous Intensity Luminous Intensity

The intensity of light depends on its:

1 Mark(s)

Your Answer:

Frequency Frequency
Amplitude Amplitude
Wavelength Wavelength
Velocity Velocity

Albert Einstein was awarded the Nobel Prize for his work on:

1 Mark(s)

Your Answer:

Theory of Relativity Theory of Relativity
Photoelectric Effect Photoelectric Effect
Wave Theory Wave Theory
Black Hole Theory Black Hole Theory

A particle is projected from the ground with velocity $u$ at angle $\theta$. Its average velocity between the point of projection and the highest point is:

1 Mark(s)

Your Answer:

$u \cos\theta$ $u \cos\theta$
$u/2$ $u/2$
$\frac{u}{2}\sqrt{1+3\cos^2\theta}$ $\frac{u}{2}\sqrt{1+3\cos^2\theta}$
$u$ $u$

A rocket with a lift-off mass of $20,000$ kg is blasted upwards with an initial acceleration of $5 m/s^2$. The initial thrust (force) is ($g=10$):

1 Mark(s)

Your Answer:

$200,000 N$ $200,000 N$
$100,000 N$ $100,000 N$
$300,000 N$ $300,000 N$
$400,000 N$ $400,000 N$

The equation of trajectory of a projectile is given by $y = \sqrt{3}x - g x^2 / 2$. The angle of projection is:

1 Mark(s)

Your Answer:

$30^\circ$ $30^\circ$
$45^\circ$ $45^\circ$
$60^\circ$ $60^\circ$
$90^\circ$ $90^\circ$

The definition of the meter is currently based on:

1 Mark(s)

Your Answer:

Length of a platinum bar Length of a platinum bar
Earth's circumference Earth's circumference
Speed of light in vacuum Speed of light in vacuum
Wavelength of Krypton-86 Wavelength of Krypton-86

The minimum velocity required to project a body so that it never returns to Earth is called:

1 Mark(s)

Your Answer:

Orbital Velocity Orbital Velocity
Terminal Velocity Terminal Velocity
Escape Velocity Escape Velocity
Critical Velocity Critical Velocity

In SHM, the acceleration is directly proportional to:

1 Mark(s)

Your Answer:

Velocity Velocity
Time Time
Displacement Displacement
Frequency Frequency

1 nanometer is equal to:

1 Mark(s)

Your Answer:

$10^{-6} m$ $10^{-6} m$
$10^{-9} m$ $10^{-9} m$
$10^{-10} m$ $10^{-10} m$
$10^{-12} m$ $10^{-12} m$

Which of the following is NOT a fundamental SI unit?

1 Mark(s)

Your Answer:

Meter Meter
Kelvin Kelvin
Newton Newton
Candela Candela

What is the dimensional formula of the Universal Gas Constant ($R$)?

1 Mark(s)

Your Answer:

$[ML^2T^{-2}K^{-1}mol^{-1}]$ $[ML^2T^{-2}K^{-1}mol^{-1}]$
$[MLT^{-2}K^{-1}]$ $[MLT^{-2}K^{-1}]$
$[ML^2T^{-1}K]$ $[ML^2T^{-1}K]$
$[M^{-1}L^2T^{-2}K]$ $[M^{-1}L^2T^{-2}K]$

A wire elongates by $l$ when a load $W$ is hung from it. If the wire goes over a pulley and two weights $W$ each are hung at the two ends, the elongation of the wire will be:

1 Mark(s)

Your Answer:

$l/2$ $l/2$
$l$ $l$
$2l$ $2l$
Zero Zero

If kinetic energy of a body is conserved, then:

1 Mark(s)

Your Answer:

Momentum is always conserved Momentum is always conserved
Force acting is zero Force acting is zero
Net work done on it is zero Net work done on it is zero
It moves in a straight line It moves in a straight line

The audible range of sound for human beings is:

1 Mark(s)

Your Answer:

10 Hz - 1000 Hz 10 Hz - 1000 Hz
20 Hz - 20 kHz 20 Hz - 20 kHz
20 kHz - 50 kHz 20 kHz - 50 kHz
1 kHz - 100 kHz 1 kHz - 100 kHz

If a person sitting on a rotating chair stretches his arms, the angular speed:

1 Mark(s)

Your Answer:

Increases Increases
Decreases Decreases
Remains same Remains same
Becomes zero Becomes zero

What is the dimensional formula of 'Surface Tension'?

1 Mark(s)

Your Answer:

$[MLT^{-2}]$ $[MLT^{-2}]$
$[ML^2T^{-2}]$ $[ML^2T^{-2}]$
$[MT^{-2}]$ $[MT^{-2}]$
$[ML^{-1}T^{-2}]$ $[ML^{-1}T^{-2}]$

Given Young's modulus $Y$, Density $\rho$. The speed of sound in a solid rod is given by:

1 Mark(s)

Your Answer:

$\sqrt{Y/\rho}$ $\sqrt{Y/\rho}$
$\sqrt{\rho/Y}$ $\sqrt{\rho/Y}$
$Y\rho$ $Y\rho$
$\sqrt{Y\rho}$ $\sqrt{Y\rho}$

A cable that can support a load $W$ is cut into two equal parts. The maximum load that each part can support is:

1 Mark(s)

Your Answer:

$W$ $W$
$W/2$ $W/2$
$2W$ $2W$
$W/4$ $W/4$

To break a wire, a force of $10^6 N/m^2$ is required. If the density of the material is $3 \times 10^3 kg/m^3$, then the length of the wire which will break by its own weight is:

1 Mark(s)

Your Answer:

$3.4 m$ $3.4 m$
$33.3 m$ $33.3 m$
$300 m$ $300 m$
$340 m$ $340 m$

The pressure exerted by an ideal gas is given by:

1 Mark(s)

Your Answer:

$\rho v^2$ $\rho v^2$
$\frac{1}{2} \rho v^2$ $\frac{1}{2} \rho v^2$
$\frac{1}{3} \rho \bar{v}^2$ $\frac{1}{3} \rho \bar{v}^2$
$\frac{2}{3} \rho \bar{v}^2$ $\frac{2}{3} \rho \bar{v}^2$

The resolving power of a telescope increases when the aperture diameter:

1 Mark(s)

Your Answer:

Increases Increases
Decreases Decreases
Remains same Remains same
Is halved Is halved

The tension in a string is:

1 Mark(s)

Your Answer:

Gravitational force Gravitational force
Electromagnetic force Electromagnetic force
Nuclear force Nuclear force
Weak force Weak force

Evaluating Your Answers

PAF Physics Academic Test : Question 1 of 75