Mark the correct alternative in the following:

The distance moved by a particle travelling in a straight line in t seconds is given by s = 45t + 11t2 – t3. The time taken by the particle to come to rest is


If we are given the distance travelled(s) as a function of time, we can calculate velocity(v) by


s = 45t + 11t2 – t3


Differentiating with respect to time, we get



If the particle is at rest, then its velocity will be 0


v(t)=45+22t-3t2=0


Solving the quadratic equation, we get


or t=9 sec


Since time can’t be negative therefore t=9secs.

1