A Model Rocket with a Mass of 500 Grams Is

Multiple Choice

A model rocket with a mass of 500 grams is launched straight up. It achieves a speed of 20.0 m/s in 2.00 seconds. Ignoring any change in mass of the rocket due to expelled fuel, and neglecting air resistance, the average thrust force of the engines on the rocket is

A) 7.50 N.
B) 9.90 N.
C) 12.0 N.
D) 13.5 N.
E) 20.0 N