physics
posted by maggie .
A 4.0 kg particle is moving along the x axis to the left with a velocity of v= 12.0 m/s. Suddenly, between times t =0 and t = 4.0 x a net force = 3t^2 – 12t is applied to the particle, where F is in N and t is in s. Calculate the velocity of the particle at t=4.0 s. Can I just substitute 4 in this formula 3t^2  12t to solve

you have to calculate acceleration.
a= force/mass= (3t^212t)/4
v(4)=12+a*t
now put t=4 into the equation