问题 问答题

有一些航空母舰上装有帮助起飞的弹射系统,已知某型号的战斗机在跑道上加速时,可能产生的最大加速度为5m/s2,起飞速度为50m/s,如果要求该飞机滑行100m后起飞,那么,弹射系统必须使飞机具有多大的速度才能让飞机起飞?

答案

设弹射系统使飞机具有速度v0飞机就能起飞由

v2t
-
v20
=2as知:

(50 m/s)2-

v20
=2×5 m/s2×100 m,

v0=10

15
m/s.

答:弹射系统必须使飞机具有10

15
m/s的速度才能让飞机起飞.

单项选择题
单项选择题

Emotion is a feeling about or reaction to certain important events or thoughts. People enjoy feeling such pleasant emotions as love, happiness, and contentment. They often try to avoid feeling unpleasant emotions, such as loneliness, worry, and grief.
Individuals communicate most of their emotions by means of words, a variety of sounds, facial expressions, and gestures. For example, anger causes many people to frown, make a fist, and yell. People learn ways of showing some of their emotions from members of their society, though heredity (遗传)may determine some emotional behavior. Research has shown that different isolated peoples show emotions by means of similar facial expressions.
Charles Darwin, famous for the theory of natural selection, also studied emotion. Darwin said in 1872 that emotional behavior originally served both as an aid to survival and as a method of communicating intentions. According to the James-Lange theory of emotions developed in the 1880s, people feel emotions only if aware of their own internal physical reactions to events, such as increased heart rate or blood pressure. But this theory was not up-held: by research on cats that had their nervous system damaged. The cats could not feel their body’s internal changes, but they showed normal emotional behavior. John B. Watson, an American psychologist who helped found the school of psychology called behaviorism, observed that babies stimulated by certain events showed three basic emotions--fear, anger, and love. Watson’s view has been challenged frequently since he proposed it in 1919.
The most widely accepted view is that emotions occur as a complex sequence of events. The sequence begins when a person encounters an important event or thought. The person’s interpretation of the encounter determines the feeling that is likely to follow. For example, someone who encounters a bear in the woods would probably interpret the event as dangerous. The sense of danger would cause the individual to feel fear. Each feeling is followed by physical changes and desires to take action, which are responses to the event that started the sequence. Thus, a person who met a bear would probably run away.
Several American psychologists independently developed the theory that there are eight basic emotions. These emotions--which can exist at various levels of intensity--are anger, fear, joy, sadness, acceptance, disgust,
surprise, and interest or curiosity. They combine to form all other emotions, just as certain basic colors produce all others.

In the sequence of events for emotions to occur, which is next to the encounter of an important event

A. Interpretation made.
B. Responses produced.
C. Feeling stimulated.
D. Action taken.