题干

如图甲所示,将一个5.4kg质量分布均匀的长方体物块水平放置在水平桌面上,物块的长0.2m,宽0.1m,高0.1m,求:

①物块的密度是多少kg/m3

②图甲中,物块水平放置时对桌面的压强是多少Pa?

③图乙中,把物块竖直放置于足够大的容器内,然后倒入水,直至水深0.3m,物块受到水的浮力是多少N?

上一题 下一题 0.0难度 选择题 更新时间:2015-08-18 11:50:08

答案(点此获取答案解析)

①物体的体积为V=abh=0.2m×0.1m×0.1m=0.002m3
物体的密度为ρ=
m
V
= 5.4

同类题2

阅读下面短文,从短文后各题所给四个选项(A、B、C和D)中,选出可以填入空白处的最佳选项。

    A man in Pakistan is now working to help children get an education. When he was a child, he did not go to school because he was too poor.

    It is reported that Pakistan has 25 million children who do not go to school. That is the second ­highest number in the world. Only Nigeria has more. Many Pakistani children must work to support their families.

    Mohammad Ayub was once one of those children. He is now a firefighter. He also manages a small school. VOA recently visited the school in the capital Islamabad.

    Ayub started with just one student in 1982. He saw a boy cleaning cars for days. He asked him, "Why don't you go to school?" The boy answered that his parents were dead and he had to work to help support his five brothers and three sisters.

    Ayub was also an orphan and he, too, had to work to help support his five brothers and three sisters. He said, "When my father died, everyone who came to the funeral said they were sorry, but no one helped." He sold newspapers and did other work to earn enough money to pay school fees for his brothers and sisters.

    Ayub wanted to help the young boy who washed cars, but he did not have enough money to pay the boy's school fees.

    Today, Ayub teaches many children at his school in a public park. Some of the children attend other schools in the morning, but come to Ayub in the afternoon to get help with their homework.

    Ayub has helped a large number of poor children since he began teaching. Many of them come from very poor areas near the park.

    Ayub said," I used to argue with kids who worked ' Why are you washing someone's dishes or their clothes? Why don't you study? ' "

    One of the children he advised to attend classes was Farhat Abbas. Ayub found him working with his friends about 12 years ago. "He followed us back home. He told our parents he wanted to teach us and asked them to send us to his school, "Abbas said.

    Today, Abbas is taking classes at a college and is helping Ayub.

    Many children are out of school, and those who do attend classes often get a poor education. Information gathered by an organization shows half of all Pakistani children in the 5th grade do not understand basic mathematics and cannot read a story in their language.

    A group in Islamabad reports Pakistan spends less on education than any other country in South Asia.