L2
讲座
1. What is the main purpose of the lecture?
To show how technological innovations influenced the development of rockets
To explain why early experiments in rocket d esign were not successful
To explain how Newton formulated his third law of motion
To clarify the implications of Newton’s third law of motion for rocket travel
2. Why does the professor mention a chair with wheels?
To help the students understand the concept of an equal and opposite reaction
To give the students a sense of how unstable early rocket models often were
To explain how Goddard got the idea for an experiment
To introduce a formula based on Newton ‘s laws
3. What point does the professor make when he talks about an oxidizer?
Rocket motion requires the expulsion of gas through a very small opening.
Oxygen is necessary for fuel to power a rocket ship.
The fuel used in rockets is very rich in oxygen.
The forces that move a rocket are different from those that move an object on Earth.
4. According to the professor, what reason did people give for the argument that a rocket could not be used to travel in space?
Rocket fuel would not burn in a vacuum.
The rocket’s exhaust would have nothing to push against.
The force created by the burning fuel would interfere with the rocket’s movement.
The force created would be too weak to push the rocket the required distances.
5. According to the professor, how did Goddard’s experiment differ from earlier experiments with rockets?
Goddard invented the fuel used to ignite the firing chambers.
The experiment was performed in a sealed, airless tank.
Goddard was able to successfully launch a rocket into space.
The forces of action and reaction were carefully calculated.
6. What opinion does the professor express about Goddard’s experiment?
It was essential for the development of rocket science.
Its findings did not demonstrate Newton’s third law of motion.
It did not get the publicity it deserved.
It was more complicated than necessary.
