NCERT Class 11 Physics Solutions: Chapter 3 – Motion in a Straight Line Part 9

Doorsteptutor material for NCO Class-11 is prepared by world's top subject experts: fully solved questions with step-by-step explanation- practice your way to success.

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

Graph Shows the X- T Plot of One Dimensional Motion

Loading Image


  • No. The x-t graph of a particle moving in a straight line for and on a parabolic path forcannot 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: