Work, Energy And Power CBSE Questions & Answers

Work, Energy And Power

This is Physics Class 11 Work, Energy and Power CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
The scalar product of two vectors A and B is
  • A
    a tensor
  • B
    a complex number
  • C
    vector
  • D
    a scalar
    Correct
2
The scalar product of two vectors A and B in terms of the magnitudes and angle ϴ is
  • A
    \(\left| {\bf{A}} \right|\left| {\bf{B}} \right|{\rm{cos}}\theta \)
    Correct
  • B
    \(\left| {\bf{A}} \right|\left| {\bf{B}} \right|{\rm{sin}}\theta \)
  • C
    \(\left| {\bf{A}} \right|\left| {\bf{B}} \right|{\rm{tan}}\theta \)
  • D
    \(\left| {\bf{A}} \right|\left| {\bf{B}} \right|{\rm{cot}}\theta \)
3
The scalar product of two vectors A and B in terms of the projections of the vectors on the x, y and z axis is
  • A
    \({\bf{A}}{\bf{B}} = {{\rm{A}}_{\rm{x}}}{{\rm{B}}_{\rm{x}}} + {{\rm{A}}_{\rm{y}}}{{\rm{B}}_{\rm{y}}} + {{\rm{A}}_{\rm{z}}}{{\rm{B}}_{\rm{z}}}\)
    Correct
  • B
    \({\bf{A}}{\bf{B}} = {{\rm{A}}_{\rm{x}}}{{\rm{B}}_{\rm{x}}} - {{\rm{A}}_{\rm{y}}}{{\rm{B}}_{\rm{y}}} - {{\rm{A}}_{\rm{z}}}{{\rm{B}}_{\rm{z}}}\)
  • C
    \({\bf{A}}{\bf{B}} = {{\rm{A}}_{\rm{x}}}{{\rm{B}}_{\rm{x}}} - {{\rm{A}}_{\rm{y}}}{{\rm{B}}_{\rm{y}}} + {{\rm{A}}_{\rm{z}}}{{\rm{B}}_{\rm{z}}}\)
  • D
    \({\bf{A}}{\bf{B}} = {{\rm{A}}_{\rm{x}}}{{\rm{B}}_{\rm{x}}} + {{\rm{A}}_{\rm{y}}}{{\rm{B}}_{\rm{y}}} - {{\rm{A}}_{\rm{z}}}{{\rm{B}}_{\rm{z}}}\)
4
The scalar product of vectors is
  • A
    commutative and distributive
    Correct
  • B
    commutative and not distributive
  • C
    non commutative and not distributive
  • D
    non commutative and distributive
5
The change in kinetic energy of a particle is equal to the
  • A
    work done on it by some force
  • B
    work done on it by the net force
    Correct
  • C
    work done on it by the aerodynamic force
  • D
    loss in ambient kinetic energy
6
The work done by the force is defined to be
  • A
    the product of component of the force in the direction perpendicular to displacement and the magnitude of the displacement
  • B
    the product of force and the magnitude of the displacement
  • C
    the negative product of component of the force in the direction of the displacement and the magnitude of this displacement
  • D
    the product of component of the force in the direction of the displacement and the magnitude of the displacement
    Correct
7
If F is a force and d is the displacement then the work done by the force is given by
  • A
    F.d
    Correct
  • B
    - F.d
  • C
    2F.d
  • D
    -2F.d
8
In which case is the work done zero?
  • A
    Force and displacement are at an angle of 45\(^\circ \)
  • B
    Force and displacement are at an angle of 75\(^\circ \)
  • C
    Force and displacement are perpendicular to each other
    Correct
  • D
    Force and displacement are in the same direction
9
The S.I unit of force is
  • A
    Joule
    Correct
  • B
    dyne
  • C
    Newton
  • D
    erg
10
In a graph of F(x) vs x, the area under the curve
  • A
    represents the momentum of F(x).
  • B
    represents work done by F(x).
    Correct
  • C
    represents energy of F(x).
  • D
    represents the impulse of F(x)
11
work-energy theorem does not give information on
  • A
    work done
  • B
    time dependence
    Correct
  • C
    change in kinetic energy
  • D
    difference of kinetic energies
12
Physically, the notion of potential energy is applicable only to
  • A
    The class of forces where work done against the force gets stored up as energy.
    Correct
  • B
    The class of forces where work done against the force gets dissipated
  • C
    The class of forces where work done against the force gets converted to thermal energy
  • D
    The class of forces where work done against the force gets converted to kinetic energy
13
The work done by a conservative force
  • A
    depends on the path
  • B
    depends on both the end points as well as the path
  • C
    depends only on the end points
    Correct
  • D
    depends only on the end point and the path
14
The total mechanical energy of a system is conserved if the
  • A
    forces, doing work on it, are not conservative
  • B
    forces, doing work on it, are damped
  • C
    forces, doing work on it, are conservative
    Correct
  • D
    forces, doing work on it, are viscous
15
For a ball dropped from a tower of height h the total mechanical energy is
  • A
    the potential energy
  • B
    the sum of potential and kinetic energies
    Correct
  • C
    the difference of potential and kinetic energies
  • D
    the kinetic energy