问题 填空题

如下图所示,在斜面顶角处把两个小球p和q以大小相等、方向相反的初速度水平抛出,两球分别落在倾角为45°和60°的斜面上.若不计空气阻力,则p、q两球在空气中运动时间tp和tq之比为______,落在斜面上时的速度大小之比vp:vq=______.

答案

根据tanθ=

1
2
gt2
v0t
=
gt
2v0
,解得t=
2v0tanθ
g
.则
tp
tq
=
tan45°
tan60°
=
1
3

竖直分速度vy=gt=2v0tanθ,则落在斜面上的速度v=

v02+vy2
=v0
4tan2θ+1
.则
vp
vq
=
4×1+1
4×3+1
=
5
13

故答案为:1:

3
5
13

选择题
阅读理解

阅读理解。

     Believe it or not, the ability to choose is the power to change. If you can choose to live your life differently,

will you be the same person?

     Well, choosing to do the following few "simple" things will help to change your life.

     Review your life. Take time to go through your life and ask yourself, "If I do the same thing I do every

day, will there be a change? If I want to change, where will my first step be?"

     Make careful choices. Choose exactly what you wish to get to live your life; describe and think what you

really want.

     Keep up with chances. Find out about the possibilities and ways that can make you move toward your

goals, write them down and see which one suits you most.

     Get down to business. Start working on your goals. People may bring you down; you may have difficulties;

you will fail and want to give up. But the most important thing is never to give up.

     If you try these "simple" things, you will find that success is something for everyone, and you will finally

become what you want to be. Remember, success is more than what you hold in your hands; it is something

from the heart.

1. How many pieces Of advice does the writer give on changing one's life?

A. Three.

B. Four.

C. Five.

D. Six.

2. Once you get down to business, the most important thing is to _____.

A. see possibilities

B. set goals

C. ask for help

D. keep on trying

3. The underlined word "it" in the last paragraph refers to _____.

A. choice

B. change

C. success

D. life

4. This passage mainly discusses the relationship between _____.

A. choice and change

B. power and life

C. choice and difficulty

D. power and success