The position of a particle as a function of time t , is given by x t = a t + b t 2 - c t 3 where a ,  …

The position of a particle as a function of time t, is given by xt=at+bt2-ct3 where a, b and c are constants. When the particles zero acceleration, then its velocity will be:
  1. a+b23c
  2. a+b22c
  3. a+b2c
  4. a+b24c

Solution

x(t)=at+bt2-ct3
velocity v(t)=ddt(x)=ddtat+bt2-ct3
=a+2bt-3ct2
Acceleration =ddtv(t)=2b-6tc
acceleration=02b-6tc=0
t=b3c
velocity when t=b3c,
vt=b3c=a+2bb3c-3b3c2
=a+2b23c-b23c
=a+b23c

Asked in: JEE Main 2019 (09 Apr Shift 2)

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