Finding velocity equation for object moving in 2 dimensions

Travelling at 40m/s, right?

Which direction does the force act?

 

The OP says the 4 kg object is traveling at 40 m/s^2. Usually, the velocity of an object is given, not its acceleration. Is this how the problem was originally specified? 'Traveling' implies velocity, otherwise, one would say an object is accelerating at X m/s^2.

 

In specifying a problem, you can't mix cause and affect like this. You can either state the acceleration (and ask for something which can be deduced from that, like position, velocity..) or you can specify forces and let the acceleration be deduced.
And you still haven't said which direction the 20N acts in.