physics question

Question

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 4.0 ! 103 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?

Answer 1

Let F=ma and solve for the acceleration. So a = 105/5 = 21m/s². v=v₀ +at where v₀ =0 and v= 103m/s. So to find the time it takes to achieve this velocity solve for t which gives t= 103 m/s/21m/s² and t= 4.9s