From newtons second law of motion the rate of change of linear momentum is proportional to the resultant force. Momentum is the product of mass and the speed of a body.
In this case Momentum is 40 kg × 5 m/s = 200 kgm/s
From the same law we deduce that impulse (Ft) is equal to the change in momentum. Therefore, Ft = change in momentum.
Hence, to get the impulsive force we divide the change in momentum by time.
F = 200kgm/s ÷ 8 sec = 25 N
hence the force is 25 N
