NEET Physics Motion in a Straight Line / सरल रेखा में गति NEET PYQ-One Dimensional Motion

A particle moves in a straight line with a constant acceleration. It changes its velocity from \[10\,\,m{{s}^{-1}}\] to \[20\,\,m{{s}^{-1}}\] while passing through a distance 135 m in t-second. The value of t is [AIPMPT (S) 2008]

A) 10

B) 1.8

C) 12

D) 9

Correct Answer: D

Solution :

Key Idea: The problem requires kinematics equations of motion.

Let u and v be the First and final velocities of particle and a & s be the constant acceleration and distance covered, by it.

From third equation of motion \[{{v}^{2}}={{u}^{2}}+2as\]

\[\Rightarrow \] \[{{(20)}^{2}}={{(10)}^{2}}+2a\times 135\]

or \[a=\frac{300}{2\times 135}=\frac{10}{9}m{{s}^{-2}}\]

Now using first equation of motion,