问题 填空题

(1)用游标卡尺测量某一物体的宽度情况如图(甲)所示,其读数为______mm;

用螺旋测微器测某一物体的长度情况如图(乙)所示,其读数为______cm.

(2)某组同学想通过单摆实验测出当地的重力加速度.他们拟通过改变摆长测出对应的周期,

得到若干组周期和摆长的数据;然后建立直角坐标系,以周期平方T2为纵坐标、摆长L为横坐标作出T2-L图线.在计算重力加速度时,一位同学认为应该从上述实验数据中取出一组周期和摆长的值,利用单摆周期公式,求出重力加速度.另一位同学认为既然作出了图线,就应该利用图线求重力加速度.经分析可知图线的斜率k=

4π2
g
,则只需用量角器量出图线与横轴的夹角α,算出斜率k=tanα,然后用公式g=
4π2
k
算出重力加速度对两位同学计算重力加速度的方法作出评价,如果合理请说出理由.如果存在问题请指出,并给出你认为合理的计算方法.

答案

(1)游标卡尺的主尺读数为58mm,游标尺上第13个刻度与主尺上某一刻度对齐,故其读数为0.05×13mm=0.65mm,

所以最终读数为:58mm+0.65mm=58.65mm;

螺旋测微器的固定刻度读数为5.5mm,可动刻度读数为0.01×17.8mm=0.178mm,所以最终读数为5.678mm.

故答案为:58.65,5.678.

(2)两种方法均不妥,第一种从实验数据中取出一组周期和摆长数据,利用单摆周期公式,求出重力加速度.没有利用图象处理减小误差,计算结果可能造成较大误差.第二位同学的做法量得图线得倾角,由于两坐标比例往往不同,量得图线得倾角不一定是图线得实际倾角,计算得不一定是图线得斜率.应在图线上取两个点,算出斜率,进行计算.

故答案为:两种方法均不妥.应在图线上取相距较远的两个点,算出斜率,进行计算.

阅读理解

阅读理解

     Robert Todd Duncan was born in 1903 in the southern city of Danville, Kentucky.His mother was

his first music teacher.As a young man, he continued his music study in Indianapolis, Indiana.

     In 1930, he completed more musical education at Columbia University in New York City.Then he

moved to Washington.For fifteen years, he taught music at Howard University in Washington.At that

time, not many black musicians were known for writing or performing classical music.Teaching at

Howard gave Duncan the chance to share his knowledge of classical European music with a mainly

black student population.  He taught special ways to present the music.These special ways became

known as the Duncan Technique.

     Besides teaching, Duncan sang in several operas with performers who were all black.But it seemed

that he always would be known mainly as a concert artist.However, his life took a different turn in the

middle 1930s.At that time, the famous American music writer George Gershwin was looking for

someone to play a leading part in his new work Porgy and Bess.The music critic (评论家) of the New

York Times newspaper suggested Todd Duncan.Duncan had almost decided not to try for the part as

he knew it would not be easy to get it.But he changed his mind.He sang a piece from an Italian opera

for Gershwin.He had sung only a few minutes when Gershwin offered him the part.He became famous

because of the part in Porgy and Bess.

     Todd Duncan gained fame as an opera singer and concert artist.But his greatest love in music was

teaching.When he stopped teaching at Howard, he continued giving singing lessons in his Washington

home until the week before his death.

1. What is this passage mainly about?

A. What Robert Todd Duncan loved most.

B. How Robert Todd Duncan became famous.

C. Robert Todd Duncan and his works of music.

D. A brief introduction to Robert Todd Duncan.

2. According to Paragraph 2, while teaching at Howard University, Duncan________.

A. found special ways to present music

B. opened doors for other black classical singers

C. had the chance to know many famous black musicians

D. became known for writing and performing classical  music

3. What happened to Duncan in the middle 1930s?

A. He gave up teaching at Howard University.

B. He was introduced by the New York Times in detail.

C. He was asked to be in charge of the opera Porgy and Bess.

D. He was given a big opportunity to become an opera singer.

4. We can infer that Robert Todd Duncan didn't at first want  to try for the part mainly because_____.

A. he was too busy to do it

B. he was not interested in it

C. he was not confident enough

D. he didn't want to become famous

5. Based on the passage, what did Robert Todd Duncan love most?

A. Singing in concerts.  

B. Writing music.

C. Singing opera.  

D. Teaching music.

单项选择题