Tag: dynamics - explaining motion

Questions Related to dynamics - explaining motion

$1 N = Z  kgf$ (approx.), then what is the value of $Z$?

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. 0.1

  2. 1

  3. 10

  4. 0

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Correct Option: A
Explanation:

The kilogram-force (kgf or kgF) is a gravitational metric unit of force. It is equal to the magnitude of the force exerted by one kilogram of mass in a $10\ ms^{-2}$ gravitational field (standard gravity, a conventional value approximating the average magnitude of gravity on Earth).Therefore one kilogram-force is by definition equal to 10 N

So 1 kgf=10N
hence 1N=0.1 kgf  , Z=0.1

What is the C.G.S. unit of force? 

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. N

  2. N.m

  3. dyne

  4. dyne.cm

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Correct Option: C
Explanation:

CGS unit of Force = $dyne$
The dyne is a unit of force specified in the centimetre-gram-second (CGS) system of units, a predecessor of the modern SI. One dyne is equal to $10^{-5}$ N.

What is the ratio of CGS to MKS unit of acceleration?

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. $\dfrac{m}{cm}$

  2. $\dfrac{m}{s}$

  3. $\dfrac{cm}{s}$

  4. $\dfrac{cm}{m}$

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Correct Option: D
Explanation:

CGS unit of acceleration $= cm/s^{2}$
MKS unit of acceleration $=m/s^{2}$
So, ratio of CGS and MKS is $\dfrac{cm}{m}$

The prefix used to represent $\displaystyle { 10 }^{ -2 }$ is called

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. Milli

  2. Centi

  3. Kilo

  4. Deci

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Correct Option: B
Explanation:

The prefix used to represent $10^{-2}$ is called Centi.

1 nano metre (1 nm) is equal to

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. $\displaystyle { 10 }^{ -7 }$m

  2. $\displaystyle { 10 }^{ -9 }$m

  3. $\displaystyle { 10 }^{ 9 }$m

  4. None of these

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Correct Option: B
Explanation:
Nano meter is a very small unit of length.
$1 \ nm = 10^{-9}\  m$

SI unit of energy is joule .

physics dynamics - explaining motion summary of si units fundamental quantities system of units

  1. True

  2. False

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Correct Option: A
Explanation:

Joule $(J)$ is the SI unit of energy. So, the given statement is true.

If 1 kg wt = 10 N, the value of gravitational intensity will be 

physics dynamics - explaining motion system of unit summary of si units system of units

  1. $\displaystyle 10{ m }/{ { s }^{ 2 } }$

  2. $\displaystyle \frac { 1 }{ 10 } { m }/{ { s }^{ 2 } }$

  3. $\displaystyle 1{ m }/{ { s }^{ 2 } }$

  4. $\displaystyle \frac { 1 }{ 100 } { m }/{ { s }^{ 2 } }$

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Correct Option: A
Explanation:

If $1\,kg\,wt=10\,N=F$

Then gravitational intensity is given by,
$g=\dfrac Fm$
$=\dfrac{10 }{1}=10 m/s^2$

The magnetic field flux is expressed in

physics dynamics - explaining motion system of unit summary of si units system of units

  1. Dynes

  2. Oersted

  3. Gauss

  4. Weber

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Correct Option: D
Explanation:

Magnetic Flux is defined as the number of magnetic field lines passing through a given closed surface. It gives the measurement of the total magnetic field that passes through a given surface area. S.I. unit of magnetic flux is Weber $(Wb)$.

Which of the following class of forces is different from others?

physics dynamics - explaining motion system of unit summary of si units system of units

  1. Pulling of a cart

  2. Stretching of a coiled spring

  3. Kicking of a football

  4. Electrical force

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Correct Option: D
Explanation:

Pulling of a cart, stretching of a coiled spring and kicking of a football take place due to contact forces. A contact force is any force that requires contact to occur. But electrical force is a non contact force which acts on an object without coming physically in contact.

Which kind of waves are produced by supersonic jet planes?

physics dynamics - explaining motion system of unit summary of si units system of units

  1. Shock waves

  2. Seismic waves

  3. Infrasonic waves

  4. Infrared waves

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Correct Option: A
Explanation:

The waves produces by the supersonic jet planes are shock waves. When a wave moves faster than the local speed of sound in a fluid, it is a shock wave.