Question

A rope exerts a constant horizontal force of 250N to pull a 60 Kgcrate across the floor. The velocity of the crateis observed toincrease from 1 m/s to 3 m/s in a time of 2 secondsunder theinfluence of this force and the frictional force exertedby thefloor on the crate. What is the acceleration of the crate?What isthe magnitude of the frictional force acting on thecrate?

So with my notes I've come to theconclusion that because ofNewton's 2nd law, that different gravitational forces acton fallingobjects of different masses, but the objects havethe sameacceleration which means the acceleration of the crateis9.8 m/s^2.

But when I tried to use theequation that I have down in mynotes f=ma, to find the magnitudeof frictional force I get thrownoff because my answers don't addup and when the problem refers tovelocity I think I'm missing animportant piece. So far I tried tofind the frictional force bymultiplying the mass of 60 Kg by theacceleration of 9.8 m/s^2 andI am not getting a correct answer!Thank you for yourhelp!!!