A small rocket with mass 20.0 kg is moving in free fall toward the earth. Air resistance can be neglected. When the rocket is 80.0 m above the surface of the earth, it is moving downward with a speed of 30.0 m>s. At that instant the rocket engines start to fire and produce a constant upward force F on the rocket. Assume the change in the rocket’s mass is negligible. What is the value of F if the rocket’s speed becomes zero just as it reaches the surface of the earth, for a soft landing? (Hint: The net force on the rocket is the combination of the upward force F from the engines and the downward weight of the rocket.)

A small rocket with mass 20.0 kg is moving in free fall toward the earth. Air resistance can be neglected. When the rocket is 80.0 m above the surface of the earth, it is moving downward with a speed of 30.0 m>s. At that instant the rocket engines start to fire and produce a constant upward force F on the rocket. Assume the change in the rocket’s mass is negligible. What is the value of F if the rocket’s speed becomes zero just as it reaches the surface of the earth, for a soft landing? (Hint: The net force on the rocket is the combination of the upward force F from the engines and the downward weight of the rocket.)