Q-8. A particle is moving along a straight line and its position is given by the relation x = t 3 - 6 t 2 - 15 t + 40   m . Find
a) The time at which velocity is zero.
b) Position and displacement of the particle at that point.
c) Acceleration for the particle at that line.

d(x)= d(t3-6t2-15t+40)
d(t)       d(t)
It is given that d(x)=v=0
                          d(t)
After differentiating,
3t​2-12t-15=0
t= -1(not applicable),5
Therefore, t=5 seconds.

At x={(5)3-6(5)2-15(5)+40}
x=125-150-75+40
=60m in the opposite diection

​a=d(v)=d(3t​2-12t-15)
     d(t)        d(t)

=6t-12
At t=5sec,
=6(5)-12=18ms​-2

 

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