Tag: physics

Questions Related to physics

A positron is emitted from $\mathrm{N}\mathrm{a} _{11}^{23}$. The ratio of the atomic mass and atomic number of the resulting nuclide is

physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

  1. $22/10$

  2. $22/11$

  3. $23/10$

  4. $23/12$

Show answer
Correct Option: C
Explanation:

When a positron is emitted from nucleus, proton will convert into a neutron. So atomic number will be decrease by one  but atomic mass will be constant. 

Thus, atomic mass / atomic number $=23/(11-1)=23/10 $

$ _{6}^{11}\textrm{C}$ on decay produces 

physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

  1. positron

  2. $\alpha-$ particle

  3. $\beta-$ particle

  4. $ _{5}^{11}\textrm{B}$

Show answer
Correct Option: A,C,D
Explanation:

$ _{6}^{11}\textrm{C}\rightarrow _{5}^{11}\textrm{B}+ _{+1}^{0}\textrm{e}$

Masses of two isobars $ _{29}^{64}\textrm{Cu}$ and $ _{30}^{64}\textrm{Zn}$ are $63.9298 amu$ and $63.9292 amu$ respectively. It can be concluded from these data that 

physics nuclear physics beta decay change in nucleus due to radioactive decay alpha, beta and gamma particles (rays) and their properties

  1. Both the isobars are stable

  2. $^{64}Zn$ is radioactive, decaying to $^{64}Cu$ through $\beta -$ decay

  3. $^{64}Cu$ is radioactive, decaying to $^{64}Zn$ through $\lambda -$ decay

  4. $^{64}Cu$ is radioactive, decaying to $^{64}Zn$ through $\beta -$ decay

Show answer
Correct Option: D
Explanation:

Since mass of the isobar has decreased, an electron has been ejected.

Thus $^{64} _{29}Cu$ decays to $^{64} _{30}Zn$ through the $\beta - $ decay as-
$^{64} _{29}Cu\rightarrow^{64} _{30}Zn+^{0} _{-1}e$

Buoyant force is directed

physics floatation buoyancy fluid pressure option b: engineering physics

  1. upwards

  2. downwards

  3. sideways

  4. at ll directions

Show answer
Correct Option: A
Explanation:

As evident from Archimedes' principle, buoyant force is the force applied upward on any object by a fluid.

When a solid is completely immersed in a fluid, the apparent loss of weight of solid is _______ volume of fluid displaced 

physics floatation buoyancy fluid pressure option b: engineering physics

  1. more than

  2. less than

  3. equal to

  4. cant say

Show answer
Correct Option: C
Explanation:

From the principle of Archimedes, loss of weight is equal to the weight of the liquid displaced.

When a body is fully immersed in a liquid the apparent loss in the weight of body is equal to :

physics floatation buoyancy fluid pressure option b: engineering physics

  1. volume of liquid displaced by the body

  2. density of the liquid

  3. weight of liquid displaced by the body

  4. none of these

Show answer
Correct Option: C
Explanation:

According to Archimedes principle, the weight of water displaced is equal to the weight of immersed part.For a solid floating in a liquid, its weight acting vertically down at its centre of gravity is equal to the weight of the liquid displaced by the immersed part of the solid acting vertically up at its centre of buoyancy. In the floating condition, the apparent weight and the apparent density of the solid are zero and the body is said to be weightless.

State whether the weight of an iron sinker with cork combined in water will be more or less than that of the iron sinker alone in water. 

physics floatation buoyancy fluid pressure option b: engineering physics

  1. Less

  2. More

  3. Same

  4. None of the above

Show answer
Correct Option: A
Explanation:

The weight of an iron sinker with cork combined in water will be less than that of the iron sinker alone in water.
This is because upthrust on cork due to water (when completely immersed) is greater than its weight.

An incompressible liquid of density $\rho$ is contained in a vessel of uniform cross-sectional area $A$. If then atmospheric pressure is $p$, then the force acting on a horizontal plane of area a situated at a depth $d$ in liquid is given by

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $Ap+apgd$

  2. $\dfrac { p }{ A } +\dfrac { \rho gd }{ a }$

  3. $\dfrac { p+\rho gd }{ a }$

  4. $a\left( \rho\ gd+p \right)$

Show answer
Correct Option: D

A gas is enclosed in a rectangular vessel. $20 \times 10^23$ molecules of the gas strike a well of the vessel normally per second, with a velocity of 250m/s and rebound with the same speed in the opposite direction. What is the force exerted by the gas on the wall if the mass of each molecule is $5 \times 10^-23$ g ? 

physics option b: engineering physics buoyancy floatation fluid pressure

  1. 50 N

  2. 40 N

  3. 75 N

  4. 25 N

Show answer
Correct Option: A

A pump is required to lift 1000 kg of water per minute from a well 20 m deep and eject it at a rate of 20 $ms^-1$. What (horsepower engine is required for the purpose of lifting water)?

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $4.46 HP$

  2. $4.36 HP$

  3. $3.96 HP$

  4. $8.85 HP$

Show answer
Correct Option: A