题干

 如图所示,物体A在光滑斜面上自由滑下,请画出物体A所受重力的示意图.

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答案(点此获取答案解析)

解:物体的重心在物体的几何重心,重力的方向是竖直向下的,从重心起沿竖直向下的方向,画一条有向线段,用G表示.如图所示:

同类题5

   Some students, parents and teachers in Shanghai were surveyed last month. According to the result of the survey, the generation gap(代沟) between students and parents as well as teachers is becoming wider. Here is what they said.
Voice of the students:
   “Our parents hold too high expectations which put us under lots of pressure. They care too much about our lives and studies,” one student said.
   “It's impolite that some students’ parents read their children's diaries without permission!” one student said angrily.
   “Some of our teachers are so serious that we can't make friends with them at all,” another student said sadly.
Voice of the parents:
   One mother said, “After school, my daughter usually locks herself into her room and spends lots of time talking with others on the phone. And I can't stand her clothes and hairstyle!”
   “I thought my son was doing very well in his studies. I didn't realize I was being cheated by him until I got a call from his teacher,” said a father.
Voice of the teachers:
   An English teacher said, “Today, the role of the teacher is to put knowledge into students' brains. The power of teachers has kept students away from them.”
   “Some parents pay too much attention to their children's grades instead of creating a lively and colorful environment at home,” another teacher said.
   “In the past, teachers and students often played games together or talked with each other. Today, only studies and grades are talked about,” said a teacher. “A school should be a place where students can learn not only knowledge, but also how to face failure and frustration bravely enough.