A Test Rocket at Ground Level Is Fired Straight Up

Multiple Choice

A test rocket at ground level is fired straight up from rest with a net upward acceleration of 20 m/s².After 4.0 s,the motor turns off but the rocket continues to coast upward with insignificant air resistance.What maximum elevation does the rocket reach?

A) 160 m
B) 330 m
C) 320 m
D) 410 m
E) 490 m