Aparticle moves along the x axis with an acceleration of a=18t, where a has units if m/s2. if the particle at time t=0 is at the origin with a velocity of -12 m/s, what js its position at t=4.0s?

 Position at t= 4 seconds is 144 m

Explanation:

 It is given that acceleration, a = 18 t, where t is the time.

 We know that Velocity,

  Substituting value of a,

           Velocity,

 We know that at t = 0, v = -12 m/s

         So,

So velocity,

  We also know that displacement,

     Substituting value of v,  

        Displacement,

  We know that at t = 0, particle is at origin, x =0.

               So,  

   Displacement,

At t = 4 seconds

Position at t= 4 seconds is 144 m  

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.