A) It expands in size. B) It is heavier than cool air. C) It is less dense than cooler air. D) It has more pressure.
A) It contracts. B) It expands. C) It escapes. D) It becomes heavier.
A) The envelope. B) The burner. C) The flame. D) The basket.
A) By changing the weight of the basket. B) By adjusting the temperature of the air. C) By changing the balloon color. D) By adding more gas.
A) To let in cool air. B) To release hot air. C) To stabilize the balloon. D) To increase lift.
A) Calm and clear weather. B) Windy and cloudy weather. C) High humidity. D) Rainy conditions.
A) 5 to 10 hours. B) All day. C) 30 minutes. D) 1 to 2 hours.
A) Between 1,000 and 3,000 feet. B) Under 500 feet. C) At sea level. D) Above 10,000 feet. |