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.
To determine which option is true about the balloon, we need to analyze the forces acting on it.
First, let's consider the force of gravity. Gravity is pulling the balloon downward with a force of 21.1N. This force is always directed toward the center of the Earth and is independent of the balloon's altitude.
Next, let's consider the lift force provided by the atmosphere. The lift force counters the force of gravity and is directed upward. In this case, the lift force is 18.7N, which is less than the force of gravity.
Now, let's analyze the options:
a. The balloon rises at constant velocity.
Since the lift force (18.7N) is less than the force of gravity (21.1N), the net force acting on the balloon is downward. Therefore, the balloon will not rise at a constant velocity.
b. The net force on the balloon is upward.
Since the net force on the balloon is actually downward due to the force of gravity being greater than the lift force, option b is not true.
c. The net force on the balloon is downward.
This option is correct. The net force on the balloon is downward because the force of gravity (21.1N) is greater than the lift force (18.7N).
d. If there is no wind, the balloon will stay at the altitude at which it is released.
Since the net force on the balloon is downward, it will not stay at the same altitude. Gravity will cause it to descend unless other factors like wind intervene.
e. The balloon falls at constant velocity.
Since the forces are unbalanced, with gravity being greater than the lift force, the balloon will not fall at a constant velocity. The net force on the balloon is downward, causing it to accelerate as it falls.
Therefore, the correct option is c. The net force on the balloon is downward.