NCERT Class 11 Physics Solutions: Chapter 3 – Motion in a Straight Line Part 9 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question: 3.17

Below figure shows the plot of one-dimensional motion of a particle. Is it correct to say from the graph that the particle moves in a straight line for and on a parabolic path for ? If not, suggest a suitable physical context for this graph.

Graph Shows the X- T Plot of One Dimensional Motion


  • No. The x-t graph of a particle moving in a straight line for and on a parabolic path for cannot be shown as the given graph.
  • This is because, the given particle does not follow the trajectory of path followed by the particle as
  • A physical situation that resembles the above graph is of a freely falling body held for sometime at a height

Question 3.18:

A police van moving on a highway with a speed of fires a bullet at a thief՚s car speeding away in the same direction with a speed of . If the muzzle speed of the bullet is with what speed does the bullet hit the thief՚s car? (Note: Obtain that speed which is relevant for damaging the thief՚s car) .


  • Speed of the police van,

  • Muzzle speed of the bullet,
  • Speed of the thief՚s car,
  • Since the bullet is fired from a moving van, its resultant speed can be obtained as:
  • Since both the vehicles are moving in the same direction, the velocity with which the bullet hits the thief՚s car can be obtained as: