Question
A particle moves in a straight line with a constant acceleration. It changes its velocity from 10 ms-1 to 20 ms-1 while passing through a distance 135 m in t second. The value of t is
-
10
-
1.8
-
12
-
9
Solution
D.
9
The problem requires kinematics equations of motion
Let u and v be the first and final velocities of particle an a and s be the constant acceleration and distance covered by it.
From third equation of motion
v2 = u2 + 2as
(20)2 = (10)2 + 2a x 135
or
a = 300/2 x135 = 10/9 ms-2
Now using first equation of motion,
v= u +at
or
