问题 问答题

如图所示,质量均为2.4千克的薄壁圆柱形容器A和B放在水平地面上,底面积分别为2×10-22和1×10-22.容器A中盛有0.1米高的水,容器B中盛有质量为1.6千克的酒精.(ρ酒精=0.8×103千克/米3)求:

①容器B中酒精的体积V酒精

②容器B对水平地面的压强pB

③现有质量相等的甲、乙两实心物块,若将甲浸没在水中、乙浸没在酒精中后,两液体均未溢出,且两液体各自对容器底部压强的变化量相等,求甲、乙的密度ρ、ρ之比.

答案

①ρ=

m
V

∴V酒精=

m酒精
ρ酒精
=
1.6kg
0.8×103kg/m3
=2×10-3m3

②容器B对水平地面的压力:

FB=G=mg=(m酒精+mB)g=(2.4kg+1.6kg)×9.8N/kg=39.2N,

容器B对水平地面的压强:

pB=

FB
SB
=
39.2N
1×10-2m2
=3920Pa;

③由题知,△p=△p酒精

即:ρg△h酒精g△h酒精

ρg

V
SA
酒精g
△V酒精
SB

ρg

V
SA
酒精g
V
SB

ρg

m
ρ
SA
酒精g
m
ρ
SB

ρg

m
ρSA
酒精g
m
ρSB

ρ:ρSB:ρ酒精SA

=(1×103kg/m3×1×10-2m2):(0.8×103kg/m3×2×10-2m2)=5:8.

答:①容器B中酒精的体积为2×10-3m3

②容器B对水平地面的压强为3920Pa;

③甲、乙的密度ρ、ρ之比为5:8.

填空题
阅读理解

Many of us have heard of the saying: everything is possible if you can just believe. But few of us really know the power of faith and perseverance(坚定).  South African swimmer Natalie du Tiot embodies(体现)those virtues.

Du Tiot, 24, became the first swimmer to compete in both the Olympic Games and the Paralympics (残奥会)in Beijing. Although she finished 16th in the tough 10km marathon in the able-bodied Games, she has collected three golds in the Paralympics so far.

One of the most successful disabled athletes of all time, Natalie du Tiot was already a promising swimmer when she lost her leg in a motorcycle accident in 2001, at just 17.

“There are a lot of dark moments,” she said, “There are some days when I cry. But I try to remember that better days are ahead. You just go on.”

Within a few months, she was back in the swimming pool.

She still completes and still succeeds. The only difference is she has switched to longer events—from 200m and 400m individual medley to 800m and 1,500m freestyle—to make up for her loss of speed with only one leg. But she made no adjustment to her mental look(精神面貌).

“Going out in the water, it feels as if there’s nothing wrong with me. It doesn’t matter if you look different. You’re still the same as everybody else because you have the same dream.”

She is the owner of many world records, and she also won gold when competing against able-bodied swimmers in the 1,500m freestyle at the All African Games in 2007.

But there is no magic recipe(秘诀) for success. It all comes down to hard work and determination. “She is stubborn, which is good and bad,” said her coach Karoly Von Toros. “Good for the swimming, but bad for the coach.”

There is a poem that hangs on her wall that reads:

The tragedy (悲剧)of life does not lie in not reaching your goals;

The tragedy of life lies in not having goals to reach for.

小题1: Natalie du Tiot is a vivid example that____________________.

A.you are what you believe

B.your biggest enemy is yourself

C.results are not so important as the process

D.you must set reasonable goals or you will fail小题2:According to the text , Natalie du Tiot became________________.

A.the first athlete to compete with able-bodied swimmers in the world

B.the youngest disabled swimmer to break the world record in the 1,500m freestyle

C.the youngese disabled swimmer to collect three golds in a single Paralympics

D.the first swimmer to compete in both the Olympic Games and the Paralympics小题3:Which of the following is the correct order of the events that happened to Natalie du Tiot?

a. She won gold at the All Africa Games.

b. She finished 16th in the tough 10km marathon in the Olympics

c. She adjusted herself to long events.

d. A motorcycle accident disabled her.

A.cdab

B.dcba

C.dcab

D.dacb小题4:In dark moments it was_______________ that pushed her on.

A.her coach

B.her family

C.hope and faith

D.her love of swimming