Tag: alternative fuels and energy sources

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Questions Related to alternative fuels and energy sources

Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

A proton and a deutron both enter in a region uniform magnetic field B, moving at right angles to the field $\vec { \mathrm { B } }$  . If the radius of circular orbits for both the particles is equal and kinetic energy acquired by deutron is I Me V, then kinetic energy acquired by the proton particle will be . 

  1. 1 MeV

  2. 2 MeV

  3. 0.5 MeV

  4. 4 MeV
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$R = \dfrac{{mv}}{{qB}} = \dfrac{{\sqrt {2mk} }}{{qB}}{K _p} = \dfrac{{{q^2}{B^2}R _p^2}}{{2mp}}$

$k = \dfrac{{{q^2}{B^2}{R^2}}}{{2m}}$
$\therefore \dfrac{{{K _\infty }}}{{{K _p}}} = {\left( {\dfrac{{{q _\infty }}}{{q{I _0}}}} \right)^2}\left( {\dfrac{{{m _p}}}{{{m _\infty }}}} \right){\left( {\dfrac{{{R _p}}}{{{R _\infty }}}} \right)^2}$
$ \Rightarrow {K _\infty } = {K _p}{\left( {\dfrac{{{q _\infty }}}{{{q _p}}}} \right)^2}\left( {\dfrac{{mp}}{{{m _\infty }}}} \right){\left( {\dfrac{{{R _\infty }}}{{{R _p}}}} \right)^2}$
${K _p} = 1MeV{\left( 2 \right)^2}{\left( {\dfrac{1}{4}} \right)^2}{\left( 1 \right)^2} = 1MeV$
Hence,
option $(A)$ is correct answer.

Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

If K.E. body is increased by 100 % then % change in its momentum is:

  1. 50%

  2. 41.4%

  3. 10%

  4. 20%
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Momentum p is related to kinetic energy K by p = sqrt(2mK). If kinetic energy increases by 100 percent, the new kinetic energy becomes K2 = K + 1.0K = 2.0K. The new momentum p2 = sqrt(2m(2K)) = sqrt(2) * p = 1.414 * p, representing a 41.4 percent increase.

Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

A 200 gm mass has velocity of $(3\hat i+4\hat j)$m/s at certain instant. Find its kinetic energy. 

  1. $2.5 J$
  2. $0.5 J$
  3. $0.8 J$
  4. $1.5 J$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

First we will calculate the Magnitude of velocity  so $v=\sqrt{3^2+4^2}=5\ m/s$

Now m=200 gm or 0.2 kg

So $KE=\dfrac{mv^2}{2}=\dfrac{0.2\times 5^2}{2}$

so $KE=2.5\ J$

Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

A proton is kept at rest. A positively charged particle is released from rest at a distance $d$ in its field. Consider two experiments; one in which the charged particle is also a proton and in another, a positron. In the same time $t$, the work done on the two moving charged particles is:

  1. same as the same force law is involved in the two experiments

  2. less for the case of a positron, as the positron moves away more rapidly and the force on it weakens

  3. more for the case of a positron, as the positron moves away a larger distance.

  4. same as the work done by charged particle on the stationary proton
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
 The force between two protons is equal to the force between the proton and a position because their charges are same. As the mass of positron is much lesser than a proton, (1/1840 times) it moves away through much larger distance compared to proton. Change in their momentum will be same. So, a velocity of a lighter particle will be greater than that of a heavier particle. So, a positron is moved through a larger distance.
As $work done = force \times distance$. As forces are same in case of proton and positron but distance moved by positron is larger, hence, work done will be more.
Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

An electron and a proton are moving under the influence of mutual forces. In calculating the change in the kinetic energy of the system during motion, one ignores the magnetic force of one on another. This is because

  1. The two magnetic forces are equal and opposite, so they produce no net effect

  2. The magnetic forces do no work on each particle

  3. The magnetic forces do equal and opposite (but non-zero) work on each particle

  4. The magnetic forces are necessarily negligible
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

As the magnetic forces due to motion of electron and proton act in a direction perpendicular to the direction of motion, no work is done by these forces. That is why one ignores the magnetic force of one particle on another.

Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

A car starts from rest and moves on a surface in which the coefficient of friction between the road and the tyres increases linearly with distance (x). If the car moves with the maximum possible acceleration, the Kinetic energy (E) of the car will depend on x as:

  1. $E\propto\dfrac{1}{x^2}$
  2. $E\propto\dfrac{1}{x}$
  3. $E\propto{x}$
  4. $E\propto{x^2}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Support car moves a distance dx at a distance x.

$\mu=kx$
$f _r=kx(mg)$
Work done by friction $=K.E(E)$
$E=f _r dx=mg kx dx$
$E \propto x^2$

Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

Consider the following two statement 
A) Linear momentum of a system of particles is zero.
B) Kinetic energy of a system of particles is zero 

  1. A does not imply B and B does not imply A

  2. A Implies B but B does not imply A

  3. A does not imply B but B implies A

  4. A implies B and B implies A
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If the kinetic energy of a system of particles is zero, every particle must have zero velocity, which means the linear momentum must also be zero (so B implies A). However, if the linear momentum is zero, individual particles can still be moving in opposite directions with equal and opposite momenta, meaning kinetic energy is not necessarily zero (so A does not imply B).

Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

The kinetic energy of an electron which is accelerated through a potential of $100$ volts is?

  1. $1.602\times 10^{-17}$ joules
  2. $418.6$ calories
  3. $1.16\times 10^4$ eV
  4. $6.626\times 10^{-34}$ watt-second
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to de Broglie equation,Wavelength associated with an electron through potential difference V is given as

$\lambda =\frac { 12.27 }{ \sqrt { V }  } A=\frac { 12.27 }{ \sqrt { 100 }  } A=\frac { 12.27 }{ 10 } A=1.227A$

Multiple choice chemistry occurrence of carbon compounds in nature substances, objects and energy alternative fuels and energy sources alternative sources of energy

Hydrogen fuel is used in:

  1. liquid-propellant rockets

  2. portable fuel cell applications

  3. cars

  4. all of above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Hydrogen fuel can provide motive power for liquid-propellant rockets, cars, boats and airplanes, portable fuel cell applications or stationary fuel cell applications, which can power an electric motor. The problems of using hydrogen fuel in cars arise from the fact that hydrogen is difficult to store in either a high pressure tank or a cryogenic tank.