Question

Please explain answer with reason​

Answer 1

Explanation:

since x=at²-bt³

then velocity is

dx/dt=d/dt(at²-bt³)

v=2at-3bt²

and acceleration is

dv/dt=d/dt(2at-3bt²)

a=2a-6bt

a):since partical came to its initial point so displacement of the partical is zero

x=a(2a/b)²-b(2a/b)³

=4a³/b²-8a³/b²

=4a³-8a³/b²

=-4a³/b²

since it is not correct

b): as it given velocity of partical is zero after t is 2a/3b

v=2at-3bt²

=2a(2a/3b)-3b(2a/3b)

=4a²/3b-2a

=4a²-2a/3b

=2a/3b

hence option c is correct

please mark it as brilliant