What is the final velocity the plane?

Question

A 45,000 kg plane flying at a velocity of 242 m/s experiences an impulse of 720,000 newtons per second. What is the final velocity of the plane?

Answer 1

Assuming the mass of the plane does not change (i.e. ignoring change in mass due to fuel consumption),

 

I = FΔt = p_f - p_i = m(v_f - v_i) ⇒

 

v_f = I/m + v_i = (720,000 N*s) / (45,000 kg) + 242 m/s

 

v_f = 258 m/s

 

By the way, units of impulse are newtons*seconds, not newtons per second.