posted by Katie .
A weather balloon is released at an altitude of 500m. The force of gravity on the balloon is 21.1n. The lift force provided by the atmosphere is 18.7n. Which of the following is true about the balloon?
a. The balloon rises at constant velocity.
b. the net force on the balloon is upward.
c. the net force on the balloon is downward.
d. If there is no wind, the balloon will stay at the altitude at which it is released.
e.The balloon falls at constant velocity.