CBSE 11TH PHYSICS - Online Test
Q1. A refrigerator's working substance
Answer : Option D
Explaination / Solution:
No Explaination.
Q2. Which of the following is not a synonym of axiom
Answer : Option C
Explaination / Solution:
An axiom or postulate is a statement/assumption that is taken to be true, to serve as a premise or starting or base point for further reasoning and arguments.
Q3. The centripetal force required for circular motion of a car such as taking a sharp turn is provided by
Answer : Option C
Explaination / Solution:
it is the force of friction that acts between tyres and road.
Q4. Axioms are
Answer : Option A
Explaination / Solution:
An axiom or postulate is a statement that is taken to be true, to serve as a premise or starting point for further reasoning and arguments.
Q5. For rolling motion without slipping the kinetic energy of the body is
Answer : Option D
Explaination / Solution:
Rolling motion without slipping involve both translation motion and rotation motion. Hence kinetic energy of body in rolling motion is the sum of both translation kinetic energy and rotational kinetic energy.
Q6. The coefficient of viscosity for a fluid is defined as the ratio of
Answer : Option D
Explaination / Solution:
The degree to which a fluid resists flow under an applied force, expressed as the ratio of the shearing stress to the velocity gradient. The coefficient of viscosity of liquids decreases as temperature increases because the bonds between molecules are weakened.
Q7. Estimate the fraction of molecular volume to the actual volume occupied by oxygen gas at STP. Take the diameter of an oxygen molecule to be 3Ao
Answer : Option C
Explaination / Solution:
Radius =
molecular volume of oxygen
Actual volume of oxygen at STP = 22400cm3
ratio of molercular volume to the actual volume =
Q8. The latent heat of vaporization is.
Answer : Option B
Explaination / Solution:
Latent heat of vaporization is actually the total amount of enthalpy (a kind of energy/heat) necessary to accomplish a phase change for a liquid or gas at the boiling/condensation point. Phase changes are generally considered at constant pressure, rather than constant volume.
Q9. According to the principle of homogeneity of dimensions
Answer : Option C
Explaination / Solution:
It would be more exact to say that "Quantities with the same units can be added and subtracted with no problem." Quantities with the same dimensions can often be added and subtracted as long as the units are correctly converted.
Q10. At resonance conditons when the forced vibrations frequency matches the natural frequency of the system, amplitude __________________ the natural frequency of the oscillator.
Answer : Option C
Explaination / Solution:
When the mass and spring have no external force acting on them they transfer energy back and forth at a rate equal to the natural frequency. In other words, to efficiently pump energy into both mass and spring requires that the energy source feed the energy in at a rate equal to the natural frequency. Applying a force to the mass and spring is similar to pushing a child on swing, a push is needed at the correct moment to make the swing get higher and higher. As in the case of the swing, the force applied need not be high to get large motions, but must just add energy to the system.
The damper, instead of storing energy, dissipates energy. Since the damping force is proportional to the velocity, the more the motion, the more the damper dissipates the energy. Therefore, there is a point when the energy dissipated by the damper equals the energy added by the force. At this point, the system has reached its maximum amplitude and will continue to vibrate at this level as long as the force applied stays the same. If no damping exists, there is nothing to dissipate the energy and, theoretically, the motion will continue to grow into infinity.
