9. How does a spacecraft leave the surface of the Earth?
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1 point
a The spacecraft produced an upward force of thrust that was equal to the downward force of gravity.
b The spacecraft produced an upward force of thrust that was greater than 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.
b 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 greater than the downward force of gravity.
To determine how a spacecraft leaves the surface of the Earth, we need to understand the balance of forces involved.
The force that holds the spacecraft on the Earth's surface is gravity, which acts downwards. In order for the spacecraft to overcome this force and lift off, it needs to generate enough upward force, called thrust.
Thrust is typically generated by rocket engines, which burn fuel and expel it at high speeds. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. The expelled gas creates a force in the opposite direction, pushing the spacecraft upwards.
Considering the given options:
a) The spacecraft would need to produce an upward force of thrust equal to the downward force of gravity for it to lift off. This scenario would result in a balanced equilibrium, but the spacecraft would not be able to overcome gravity and ascend.
c) A downward force of thrust would not be effective in lifting the spacecraft off the Earth's surface. It would provide an opposite force to gravity, but not in the right direction.
d) A downward force of thrust less than the downward force of gravity would cause the spacecraft to sink further into the Earth, rather than lift off.
Therefore, the correct option is:
b) The spacecraft needs to produce an upward force of thrust that is greater than the downward force of gravity. This additional force allows the spacecraft to overcome gravity and ascend into space.