Tag: physics

Questions Related to physics

SI unit of G is $Nm^2   kg^{-2}$. Which of the following can also be used as the SI unit of G?

  1. $m^3kg^{-1}s^{-2}$

  2. $m^2kg^{-2}s^{-1}$

  3. $m kg^{-3}s^{-1}$

  4. $m^2kg^{-3}s^{-2}$

Correct Option: A

$m^3kg^{-1}s^{2}$ is also used as the SI unit of G

The characteristic of a good unit is ..

  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

Correct Option: D

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?

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

Correct Option: C

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?
  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

Correct Option: C

We know that 

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

Which of the statements are false?

  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 $Newton$

Correct Option: C

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?

  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.

Correct Option: A,C,D
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.

The equation of a stationary wave is $Y=10\sin{\cfrac{\pi x}{4}}\cos{20\pi t}$. The distance between two consecutive nodes in meters is -

  1. 4

  2. 2

  3. 5

  4. 8

Correct Option: A

$Y = 10\sin \dfrac{{\pi x}}{4}\cos \pi t$

At nodles amplitude part is zero.
$\begin{array}{l} \Rightarrow 10\sin  \dfrac { { \pi x } }{ 4 } =0 \ \Rightarrow \dfrac { { \pi x } }{ 4 } =0,\pi ,2\pi  \ \Rightarrow x=0.x=4,x=8 \end{array}$
$\therefore 4$  is distance between two consultative node.
$\therefore$ Option $A$ is correct.

The phase change between incident and reflected sound wave from a free end is

  1. $0$

  2. $\pi $

  3. $3\pi $

  4. $2\pi $

Correct Option: A

At a free and, the wave is reflected as it is with just as change in its direction of propagation 
$y= A  \sin  ( \omega t+kx)$
$y _r= A  \sin  (\omega t-kx)$
phase difference in time domain $= 0$

Regarding open organ pipe, which of following is correct?

  1. Both ends are pressure antinodes

  2. Both ends are displacement nodes

  3. Both ends are pressure nodes

  4. Both (1)and (2)

Correct Option: C

Regarding open pipe both ends are pressure nodes.

So, option $C$ is correct.

What characteristics of a point on the string will you use to find the location of the antinode

  1. displacement

  2. velocity

  3. wavelength

  4. time

Correct Option: A

An antinode is a point on the string, where the amplitude at that point is maximum 

The correct option is (a)