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NEET-XI-Physics

04: Motion in a plane

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04-Motion in a plane
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  • Qstn #1
    State, for each of the following physical quantities, if it is a scalar or a vector:
    volume, mass, speed, acceleration, density, number of moles, velocity, angular frequency, displacement, angular velocity.
    Ans : Scalars: Volume, mass, speed, density, number of moles, angular frequency.

    Vectors: Acceleration, velocity, displacement, angular velocity.
  • Qstn #2
    Pick out the two scalar quantities in the following list:

    force, angular momentum, work, current, linear momentum, electric field, average velocity, magnetic moment, relative velocity.
    Ans : Work and current are the scalar quantities in the, given list.


  • Qstn #3
    Pick out the only vector quantity in the following list:

    Temperature, pressure, impulse, time, power, total path length, energy, gravitational potential, coefficient of friction, charge.
    Ans : Impulse.
  • Qstn #4
    State with reasons, whether the following algebraic operations with scalar and vector physical quantities are meaningful:
  • #4-a
    adding any two scalars, (b) adding a scalar to a vector of the same dimensions, (c) multiplying any vector by any scalar, (d) multiplying any two scalars, (e) adding any two vectors, (f) adding a component of a vector to the same vector.


    Ans : No, because only the scalars of same dimensions can be added.

    (b) No, because a scalar cannot be added to a vector.

    (c) Yes, multiplying a vector with a scalar gives the scalar (number) times the vector quantity which makes sense and one gets a bigger vector. For example, when acceleration A is multiplied by mass m, we get a force F = ml

    (d) Yes, two scalars multiplied yield a meaningful result, for example multiplication of rise in temperature of water and its mass gives the amount of heat absorbed by that mass of water.

    (e) No, because the two vectors of same dimensions can be added.

    (f) Yes, because both are vectors of the same dimensions.

  • #4-b
    adding a scalar to a vector of the same dimensions,
    Ans : No, because a scalar cannot be added to a vector.

  • #4-c
    multiplying any vector by any scalar,
    Ans : Yes, multiplying a vector with a scalar gives the scalar (number) times the vector quantity which makes sense and one gets a bigger vector. For example, when acceleration A is multiplied by mass m, we get a force F = ml

  • #4-d
    multiplying any two scalars,
    Ans : Yes, two scalars multiplied yield a meaningful result, for example multiplication of rise in temperature of water and its mass gives the amount of heat absorbed by that mass of water.

  • #4-e
    adding any two vectors,
    Ans : No, because the two vectors of same dimensions can be added.

  • #4-f
    adding a component of a vector to the same vector.


    Ans : Yes, because both are vectors of the same dimensions.

  • Qstn #5
    Read each statement below carefully and state with reasons, if it is true or false:
  • #5-a
    The magnitude of a vector is always a scalar.
    Ans : True, magnitude of the velocity of a body moving in a straight line may be equal to the speed of the body.

  • #5-b
    Each component of a vector is always a scalar.
    Ans : False, each component of a vector is always a vector, not scalar.

  • #5-c
    The total path length is always equal to the magnitude of the displacement vector of a particle.
    Ans : False, total path length can also be more than the magnitude of displacement vector of a particle.

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