问题 多选题

一物体从水平抛出到落地通过的位移s=25m,此位移与水平方向间的夹角为θ=53°,已知sin53°=0.8,cos53°=0.6,g=10m/s2,则下列说法正确的是(  )

A.物体的水平位移为20m

B.物体下落的高度为15m

C.物体的飞行时间为2s

D.物体抛出时的初速度为7.5m/s

答案

A、物体的水平位移x=scos53°=25×0.6m=15m.故A错误.

    B、物体下落的高度h=ssin53°=25×0.8m=20m.故B错误.

    C、根据h=

1
2
gt2得,t=
2h
g
=
40
10
s=2s
.故C正确.

    D、平抛运动的初速度v0=

x
t
=
15
2
m/s=7.5m/s.故D正确.

故选CD.

阅读理解

阅读表达。

     I like watching TV very much for I think it has many advantages. First of all, watching TV is a good rest.

After a day of hard work, we need a good rest. Watching TV can make our mind and body not tired any more

because of the pleasant music and TV plays.

     Besides, watching TV is entertaining. There are many kinds of entertainments, such as sports activities,

singing and dancing concerts, plays and the activities within a short time. We need at least ten hours to fly

from New York to Paris, a week by train from Beijing to Moscow and an hour to drive from Queens District

to Manhattan District. But within just one second, TV can bring us from an NBA game in New York to a

fashion show in Paris by changing the channels.

     Most important, watching TV is educational. Our children can learn every kind of subjects through the

educational programs and the special reports on TV, and it's easy for them to learn Chinese from a Chinese

teacher in Beijing and to learn Russian lessons from a Russian teacher in Moscow. Even we can learn how to

behave well from the TV plays. Meanwhile, a teacher can teach millions of students without a huge classroom.

1. What's the best title for the text?

    ________________________________________________________________________________.

2. According to the writer what's the most important reason for watching TV?

    ________________________________________________________________________________.

3. Why can watching TV make the writer have a good rest?

    ________________________________________________________________________________.

4. Why is it not possible for us to go to every place to enjoy all the activities within a short time?

    ________________________________________________________________________________.

5. Why is watching TV educational?

    ________________________________________________________________________________.

单项选择题