Question

if s=3t^2-6t+t^3.Find the average speed & velocity in t=1.5 second.

Answer 1

Answer:

S = t³-6t²-15t+12

v = dS/dt =velocity

v = 3t²-12t-15

a= accleration = dv/dt

a= 6t-12

a= 0 (given)

so 6t-12 =0

t=2 sec

Now we want to find velocity when a=0,a is zero when t=2sec.

v =3t²-12t-15

Put t=2 sec

v=3(2)²-12(2)-15

v=-27m/s

Answer 2

S = t³-6t²-15t+12

v = dS/dt =velocity

v = 3t²-12t-15

a= accleration = dv/dt

a= 6t-12

a= 0 (given)

so 6t-12 =0

t=2 sec

Now we want to find velocity when a=0,a is zero when t=2sec.

v =3t²-12t-15

Put t=2 sec

v=3(2)²-12(2)-15

v= -27 m/s