Scientists are experimenting with a kind of gun that may eventually be used to fire payloads directly into orbit. in one test, this gun accelerates a 5.0 kg projectile from rest to a speed of 4000 m/s. the net force accelerating the projectile is 4.9 × 105 n. how much time is required for the projectile to come up to speed? scientists are experimenting with a kind of gun that may eventually be used to fire payloads directly into orbit. in one test, this gun accelerates a 5.0 kg projectile from rest to a speed of 4000 m/s. the net force accelerating the projectile is 4.9 × 105 n. how much time is required for the projectile to come up to speed?