How many newtons of force are represented by the following amount: 3 kg•m/sec²? Justify your answer

The definition of 1 Newton is "the force required to accelerate

one kilogram of mass at the rate of one meter per second squared".

That set of units can be written like this:

1 N = 1 kg-m/sec².

So 3 kg-m/sec² = 3 newtons.