What is a good scientific question on a baloon powered car? (it's for my science fair)

Balloon powered car works on the principle of Newtons III law. Escaping air from the balloon, the car accelerates forward. The reaction is the air behind the car, pushing against it, and with the same force car moves forward is the action.

Some scientific questions are:

1. What is the energy stored in the balloon?

Ans: Potential energy (Potential energy is stored in elastic balloon)

2. Which energy is used in balloon-powered car?

Ans: Kinetic energy. (Whenever the balloon escapes the air, potential energy is converted into Kinetic energy)

3. What is the principle involved in balloon powered car?

Ans: Newtons III law.

what was the answer?

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.