Question 6 (1 point)
The picture below shows the Apollo spacecraft that took astronauts to the Moon in 1969. The spacecraft weighed 6.1 million pounds, and its motors produced 7.5 million pounds of thrust. Explain how the spacecraft left the surface of the earth.
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a
The spacecraft produced an upward force of thrust that was greater than the downward force of gravity.
b
The spacecraft produced an upward force of thrust that was equal to the downward force of gravity.
c
The spacecraft produced a downward force of thrust that was equal to the downward force of gravity.
d
The spacecraft produced a downward force of thrust that was less than the downward force of gravity.
a) The spacecraft produced an upward force of thrust that was greater than the downward force of gravity.
Question 7 (1 point)
An engineer wants to build a race car which will be able to speed up and slow down quickly. She is trying to determine which material to use to build the car. The table shows the materials she can choose from. Which material would best allow the car to speed up and slow down quickly?
a
aluminum
b
copper
c
steel
d
lead
a) aluminum
The correct answer is:
a) The spacecraft produced an upward force of thrust that was greater than the downward force of gravity.
Explanation:
The spacecraft left the surface of the Earth by utilizing the principle of rocket propulsion. Rocket engines work on the principle of action and reaction, or Newton's Third Law of Motion. The engines produced thrust by expelling high-speed gases in a downward direction. According to Newton's Third Law, for every action, there is an equal and opposite reaction. Therefore, when the engines expelled gases downward with a force of 7.5 million pounds of thrust, an equal and opposite force acted on the spacecraft in an upward direction. This upward force, or thrust, was greater than the downward force of gravity, which allowed the spacecraft to overcome Earth's gravitational pull and leave the surface.