Tag: substances, objects and energy

Quizzes (5) Questions (175)

Questions Related to substances, objects and energy

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

Which of the following is not a gaseous fuel?

  1. CNG

  2. Coal gas and water gas

  3. Gobar gas and acetylene

  4. Liquid hydrogen.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Solid fuels include peat, coal, wood, biomass.
Liquid fuels include petroleum, alcohol.
Gaseous fuel includes natural gas.
Liquid hydrogen (LH2 or LH2) is the liquid state of the element hydrogen.
Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

Which one of the following is not a characteristic of a good fuel?

  1. No emission of smoke or harmful gases

  2. High ignition temperature

  3. High calorific value

  4. Not much ash(residue) after burning
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Characteristics of a good fuel are as follows:
1. Cheap and easily available.
2. Easy to store and transport.
3. Low ash content.
4. Should not produce any harmful substances.
5. High calorific value.
6. Moderate ignition temperature. 
Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

Hydrogen is not used as a household fuel because:

  1. it is highly combustible gas

  2. its transportation is difficult

  3. Is not easily available

  4. all of these are true
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Though hydrogen has the highest calorific value, it is not used as a household fuel because:
1. It is not easily available and this makes it costly too.
2. It is highly combustible.
3. Transportation is difficult.
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 magenetic forces are necessarily negligible
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
The electric and magnetic forces are defined via the Lorentz force on a charged particle

$F =q(E +v ×B )$
The magnetic force comes from the second term which defines it to be perpendicular to the velocity and therefore displacement $dr$ so it doesn't do any work.
Multiple choice evs - i substances, objects and energy renewable resources alternative fuels and energy sources alternative sources of energy

A sealed container with negligible coefficient of volumetric expansion contains helium (a mono-atomic gas). When it is heated from 300 K to 600 K, the average KE of helium atoms is:

  1. halved

  2. unchanged

  3. doubled
  4. increased by factor $\sqrt2$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$the\quad avarage\quad KE\quad of\quad n\quad moles\quad of\quad gas\quad at\quad temp\quad T\quad is\quad \dfrac { 3 }{ 2 } nRT\ when\quad temp\quad is\quad doubled\quad \dfrac { 3 }{ 2 } nR(2T)=2\times \dfrac { 3 }{ 2 } nRT\ so\quad KE\quad doubles$

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

If a man speed up 1m/s his KE increases by 44% His original speed in m/s is 

  1. 1

  2. 2

  3. 5

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

Let initial KE be K = 1/2mv^2. New KE is 1.44K = 1/2m(v+1)^2. Taking the ratio: 1.44 = (v+1)^2 / v^2. Taking the square root: 1.2 = (v+1)/v. Thus, 1.2v = v + 1, so 0.2v = 1, which means v = 5 m/s.

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

A point in the object where entire mass of an object is said to be concentrated is:

  1. Point of Buoyancy

  2. Centre of Mass

  3. Point of Pressure

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A point where entire mass of the body is assumed to be concentrated is called center of mass. This point may or may be inside body or outside.