如图,一货车以v1=15m/s的速度匀速驶向十字路口,当它距路口AB线x1=17

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问题:

如图,一货车以v1=15m/s的速度匀速驶向十字路口,当它距路口AB线x1=175m 时发现另一条路上距路口中心O点x2=500m处,一辆轿车以v2=20m/s的速度开向路口,货车司机感觉到轿车“来势凶猛”,决定制动匀减速以避让轿车,而轿车仍然匀速运动.在下面的问题中,轿车和货车都看作质点.

(1)如果货车立即制动做匀减速运动,它停在AB线时,轿车有没有开过了路口中心点?

(2)如果货车迟疑了1s后制动做匀减速运动,它能在轿车刚过路口中心时恰好到达AB线吗?如能求出加速度的大小;如不能,说明理由.

考点:平均速度和瞬时速度的区别匀变速直线运动的速度与时间的关系匀变速直线运动的位移与时间的关系
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Don’t complain in the NBA
The NBA has a new rule this season. It’s called “zero tolerance”. NBA referees are not letting players complain too long or too loudly about a referee’s call. A player who does can be given a technical foul (犯规). Two technical fouls, and the player is out of the game.
The players don’t like the new rule and want the NBA to change it. They think it’s only natural to get angry during a close, hard-fought game if a call goes against you.
But I like the “zero tolerance” rule and wish other sports would follow the NBA’s example. Wouldn’t it be more enjoyable if football, soccer and tennis players stopped arguing the calls and just played the game?
The biggest reason I like the new rule is that it sets a good example to younger players. When kids see stars such as Rasheed Wallace of the Detroit Pistons shouting at the referees and arguing every call, they think it’s part of the game. But shouting at referees and arguing calls should never be part of any kid’s games. Kids should be taught to forget about the referees’ calls and pay attention to improving their skills and play their best.
All players need to learn that you control only one thing in a game, and that’s your own performance. You can’t control what the other players or trainers do. And you certainly can’t control the calls the referees make.
Finally, everyone from NBA all-stars to 8-year-olds should remember that being a basketball referee is a hard job. The referee has to make dozens of sudden calls. No hesitation. No second chances. Not even the best referee gets every call right.
Maybe if the players, trainers and fans who shout at the referees had to wear a whistle and call a few games, there wouldn’t be as many complaints about the “zero tolerance” rule.
The new rule
The players are not 小题1:      to complain too much about a referee’s call,
otherwise he might be小题2:     out of the court.
The
小题3:    opinion
They dislike the new rule and wish it to be小题4:    .
They think it’s natural for them to get angry during a close game if there is a call 小题5:     against them.
The writer’s opinion
He likes the “zero-tolerance” rule and wishes it to be followed by other sports and it would be more enjoyable if players小题6:     arguing the calls.
The new rule does小题7:     a good example to younger players.
Shouting at referees and arguing calls shouldn’t be part of any kid’s games and kids should pay attention to 小题8:      their skills and play their best.
All players can control nothing else except their own小题9:     .
Everyone should keep in mind that it’s小题10:     to be a basketball judge.
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