Motion In A Plane CBSE Questions & Answers

Motion In A Plane

This is Physics Class 11 Motion in a Plane CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
If \({A_x},{A_y}and{B_x},{B_y}\) are components of vectors A and B along the x and y axis then the sum of the vectors A and B has a component in the x direction equal to
  • A
    \({A_x} - {B_x}\)
  • B
    \( - {A_x} + {B_x}\)
  • C
    \( - {A_x} - {B_x}\)
  • D
    \({A_x} + {B_x}\)
    Correct
2
If r = \(x\hat i + y\hat j\)is the position vector of a particle then the instantaneous velocity is given by
  • A
    \(v = {{dr} \over {dt}}\)
    Correct
  • B
    \(v = 2{{dr} \over {dt}}\)
  • C
    \(v = {{dx} \over {dt}}\)
  • D
    \(v = {{dr} \over {2dt}}\)
3
If r = \(x\hat i + y\hat j\)is the position vector of a particle then the instantaneous acceleration is given by
  • A
    \(a = {{{d^3}r} \over {d{t^3}}}\)
  • B
    \(a = {{{d^2}r} \over {d{t^2}}}\)
    Correct
  • C
    \(a = {{{d^4}r} \over {d{t^2}}}\)
  • D
    \(a = {{dr} \over {dt}}\)
4
If a particle has a constant acceleration a then the position vector r in terms of initial velocity v0, initial position vector r0 and a is
  • A
    \({\bf{r}} = {{\bf{r}}_{\bf{0}}} + {{\bf{v}}_{\bf{0}}}{\rm{t}}\) +\({1 \over 2}\) \({\bf{a}}{{\rm{t}}^{\rm{2}}}\)
    Correct
  • B
    \(.{\bf{r}} = {{\bf{r}}_{\bf{0}}} + {\rm{2}}{{\bf{v}}_{\bf{0}}}{\rm{t}}\) +\({1 \over 2}\) \({\bf{a}}{{\rm{t}}^{\rm{2}}}\)
  • C
    \({\bf{r}} = {{\bf{r}}_{\bf{0}}} + {{\bf{v}}_{\bf{0}}}{\rm{t}}\) + \({\bf{a}}{{\rm{t}}^{\rm{2}}}\)
  • D
    \({\bf{r}} = {\rm{ 2}}{{\bf{r}}_{\bf{0}}} + {{\bf{v}}_{\bf{0}}}{\rm{t}}\) +\({1 \over 2}\) \({\bf{a}}{{\rm{t}}^{\rm{2}}}\)
5
For the case of uniformly accelerated motion in two dimensions it is possible to treat it as
  • A
    Two separate simultaneous one-dimensional motions with constant acceleration along one direction and a non constant acceleration along perpendicular direction.
  • B
    Two separate simultaneous one-dimensional motions with constant acceleration along a single direction.
  • C
    Two separate simultaneous one-dimensional motions with varying acceleration along one direction and a non constant acceleration along perpendicular direction
  • D
    Two separate simultaneous one-dimensional motions with constant acceleration along two perpendicular directions.
    Correct
6
if particles A and B are moving with velocities \({{\bf{v}}_{\bf{A}}}\) and \({{\bf{v}}_{\bf{B}}}\) (each with respect to some common frame of reference, say ground.). Then, velocity of particle A relative to that of B is:
  • A
    \({{\bf{v}}_{{\bf{AB}}}}\) = \({{\bf{v}}_{\bf{A}}}\) + \({{\bf{v}}_{\bf{B}}}\)
  • B
    \({{\bf{v}}_{{\bf{AB}}}}\) = - \({{\bf{v}}_{\bf{A}}}\) + \({{\bf{v}}_{\bf{B}}}\)
  • C
    \({{\bf{v}}_{{\bf{AB}}}}\) = - \({{\bf{v}}_{\bf{A}}}\) - \({{\bf{v}}_{\bf{B}}}\)
  • D
    \({{\bf{v}}_{{\bf{AB}}}}\) = \({{\bf{v}}_{\bf{A}}}\) - \({{\bf{v}}_{\bf{B}}}\)
    Correct
7
The path of a projectile is
  • A
    straight line
  • B
    hyperbola
  • C
    a parabola
    Correct
  • D
    cubic
8
Centripetal acceleration of a particle moving in a circular path with constant velocity v is given by
  • A
    \({{\rm{v}}^{\rm{2}}}/{\rm{R}}\) where R is the radius of the circle
    Correct
  • B
    \({\rm{2}}{{\rm{v}}^{\rm{2}}}{\rm{R}}\) where R is the radius of the circle
  • C
    \({\rm{2}}{{\rm{v}}^{\rm{2}}}/{\rm{R}}\) where R is the radius of the circle
  • D
    \({{\rm{v}}^{\rm{2}}}/{\rm{R}}\) where R is the radius of the circle
9
Which of the following physical quantities a vector?
  • A
    mass
  • B
    volume
  • C
    speed
  • D
    angular momentum
    Correct
10
Which of the following physical quantities a scalar?
  • A
    electric field
  • B
    velocity
  • C
    force
  • D
    work
    Correct
11
Which of the following algebraic operations on vectors not permissible?
  • A
    adding a scalar component of a vector to the same vector
    Correct
  • B
    multiplying the sum of vectors A and B by a scalar
  • C
    multiplying any vector by any scalar,
  • D
    adding any two vectors
12
Which of the following statements false?
  • A
    the total path length is always equal to the magnitude of the displacement vector of a particle
    Correct
  • B
    Three vectors not lying in a plane can never add up to give a null vector.
  • C
    the magnitude of a vector is always a scalar
  • D
    the average speed of a particle (defined as total path length divided by the time taken to cover the path) is either greater or equal to the magnitude of average velocity of the particle over the same interval of time,
13
Given vectors a, b, c, d and a + b + c + d = 0, which of the following statements not correct?
  • A
    The magnitude of (a + c) equals the magnitude of ( b + d)
  • B
    The magnitude of a can never be greater than the sum of the magnitudes of b, c, and d
  • C
    b + c must lie in the plane of a and d if a and d are not collinear, and in the line of a and d, if they are collinear
  • D
    a, b, c and d must each be a null vector
    Correct
14
Three girls skating on a circular ice ground of radius 200 m start from a point P on the edge of the ground and reach a point Q diametrically opposite to P following different paths as shown in Figure. What is the magnitude of the displacement vector for each ? For which girl is this equal to the actual length of path skate ?
Question 14 figure 1
  • A
    200 m for each; A
  • B
    200 m for each; B
  • C
    300 m for each; C
  • D
    400 m for each; B
    Correct
15
A cyclist starts from the centre O of a circular park of radius 1 km, reaches the edge P of the park, then cycles along the circumference anticlockwise from P to Q, and returns to the centre along QO as shown in Figure. If the round trip takes 10 min, what is the (a) net displacement, (b) average velocity, and (c) average speed of the cyclist ?
Question 15 figure 1
  • A
    0, 0, 11.4 km/hr
  • B
    0, 0, 27.4 km/hr
  • C
    0, 0, 21.4 km/hr
    Correct
  • D
    0, 0, 15.4 km/hr