Tag: motion and measurement

Questions Related to motion and measurement

The characteristic of a good unit is ..

physics motion and measurement guidelines for writing the units conventions for the use of si units rules to write name and symbol for units of s.i. system

  1. It should be universally accepted

  2. It should be invariable and not perishable

  3. It should be easily available & easy to reproduce

  4. All of these

Show answer
Correct Option: D
Explanation:

A good unit should contain all of the properties. 

Ans: All of these

The prefixes $nano (n), micro (\mu)$ and $pico (p)$ are often used with units.
Which row shows their correct values?

physics motion and measurement guidelines for writing the units conventions for the use of si units rules to write name and symbol for units of s.i. system

  1. $n = 10^{-6}, \mu = 10^{-9}, p = 10^{-12}$

  2. $n = 10^{-6}, \mu = 10^{-12}, p = 10^{-9}$

  3. $n = 10^{-9}, \mu = 10^{-6}, p = 10^{-12}$

  4. $n = 10^{-12}, \mu = 10^{-9}, p = 10^{-6}$

Show answer
Correct Option: C
Explanation:

1 nano unit = $10^{-9}$ unit

1 $\mu$  unit= $10^{-6}$  unit
1 $p$ unit = $10^{-12}$  unit
So, option C is correct 

Which definition is correct and uses only quantities rather than units?
physics motion and measurement guidelines for writing the units conventions for the use of si units rules to write name and symbol for units of s.i. system

  1. Density is mass per cubic metre

  2. Potential difference is energy per unit current

  3. Pressure is force per unit area

  4. Speed is distance traveled per second

Show answer
Correct Option: C
Explanation:

We know that 

Pressure $P= \dfrac{Force }{Area}$
So, option C is correct.

Which of the statements are false?

physics motion and measurement guidelines for writing the units conventions for the use of si units rules to write name and symbol for units of s.i. system

  1. The units of physical quantity represented by volume is $cm^3$

  2. The unit of physical quantity represented by mass is $ton$

  3. The work done is represented by $\dfrac{kg}{m}$

  4. The unit of physical quantity represented by weight is $Newton$

Show answer
Correct Option: C
Explanation:

Work done is given by   $W = FS $
Thus work has the units of  $kg .m s^{-2}.m$
Thus statement given in option C is incorrect.

Which of the following statements below should be followed while using the symbol for a unit of a physical quantity?

physics motion and measurement guidelines for writing the units conventions for the use of si units rules to write name and symbol for units of s.i. system

  1. The symbol named after a scientist should begin with a capital letter.

  2. They can take plural forms.

  3. They can be written in full.

  4. They should be written only in the agreed symbols while using symbols.

Show answer
Correct Option: A,C,D
Explanation:
Basic rules for the use and writing for a  unit of a physical quantity are;
1. They symbol named after scientist should have the capital letter, 
2. They can be written in full 
3. They should be written only in the agreed symbols be used while using the symbol for a unit of a physical quantity. 
4. They cannot take plural forms.

Which one of the following methods is used to measure distance of a planet or a star from the earth?

physics motion and measurement measuring length measurement of small and large distances measurement of distance

  1. Echo method

  2. Parallax method

  3. Triangulation method

  4. None of these

Show answer
Correct Option: B
Explanation:

Astronomers estimate the distance of nearby objects in space by using a method called stellar parallax, or trigonometric parallax. Simply put, they measure a star's apparent movement against the background of more distant stars as Earth revolves around the sun

'The parallax angle in radians is: $\theta = \left( 1 + \frac { 54 } { 60 } \right) \times \frac { \pi } { 180 } = 0.03316 \mathrm { rad }$
  Hence, the distance between moon and earth: 

physics motion and measurement measuring length measurement of small and large distances measurement of distance

  1. $\dfrac { \text { Diameter of Earth } } { \theta }$

  2. $\dfrac { 1.276 \times 10 ^ { 7 } m } { 0.03316 }$

  3. $3.84 \times 10 ^ { 8 } m$

  4. nnone of these

Show answer
Correct Option: C
Explanation:

Given,

$\theta =0.03316\,\,rad$

Also $b = \mathrm { AB } =$ diameter of earth $= 1.276 \times 10 ^ { 7 } \mathrm { m }$

Now d $=\dfrac{b}{\theta }=\dfrac{1.276\times {{10}^{7}}}{0.03316\,}=3.84\times {{10}^{8}}\text{m}$

Hence, distance between earth and moon is $3.84\times {{10}^{8}}\text{m}$

Which of the following instrument can be used to determine the radius of curvature of a spherical surface?

physics motion and measurement measuring length measurement of small and large distances measurement of distance

  1. Spherometer

  2. Vernier callipers

  3. Screw gauge

  4. Simple pendulum

Show answer
Correct Option: A
Explanation:

Spherometer is an instrument which is used to measure the curvature of spherical surfaces.

Parallax method is suitable for the measurement of:

physics motion and measurement measuring length measurement of small and large distances measurement of distance

  1. ball

  2. planet

  3. vehicle

  4. distance between cities

Show answer
Correct Option: B
Explanation:

Parallax method is used for the measurement of planet distance and also used to measure distance of starts and planets

option B is correct.

Which of the following is the best method to measure microscopic distances?

physics motion and measurement measuring length measurement of small and large distances measurement of distance

  1. Optical microscope

  2. Meter scale

  3. Screw gauge

  4. Diffraction pattern

Show answer
Correct Option: A
Explanation:

Optical microscopes are enabled with objective fitted with lenses with different magnifications. This helps to magnify a small objects and so necessary measurements.