Question

某實(shí)驗(yàn)小組采用如圖1所示的裝置研究“小車運(yùn)動(dòng)變化規(guī)律”．打點(diǎn)計(jì)時(shí)器工作頻率為50Hz．                                         

實(shí)驗(yàn)的部分步驟如下：                                                                                                    

a．將木板的左端墊起，以平衡小車的摩擦力；                                                               

b．在小車中放入砝碼，紙帶穿過(guò)打點(diǎn)計(jì)時(shí)器，連在小車后端，用細(xì)線連接小車和鉤碼；                                

c．將小車停在打點(diǎn)計(jì)時(shí)器附近，接通電源，釋放小車，小車拖動(dòng)紙帶，打點(diǎn)計(jì)時(shí)器在紙帶上打下一系列的點(diǎn)，斷開(kāi)電源；                                                                                                                                       

d．改變鉤碼或小車中砝碼的質(zhì)量，更換紙帶，重復(fù)b、c的操作．                                      

                                       

（1）設(shè)鉤碼質(zhì)量為m₁、砝碼和小車總質(zhì)量為m₂，重力加速度為g，則小車的加速度為：a=              （用題中所給字母表示）；                                                                                                                

（2）如圖2是某次實(shí)驗(yàn)中得到的一條紙帶，在紙帶上取計(jì)數(shù)點(diǎn)O、A、B、C、D和E，用最小刻度是毫米的刻度尺進(jìn)行測(cè)量，讀出各計(jì)數(shù)點(diǎn)對(duì)應(yīng)的刻度x，通過(guò)計(jì)算得到各計(jì)數(shù)點(diǎn)到O的距離s以及對(duì)應(yīng)時(shí)刻小車的瞬時(shí)速度v．請(qǐng)將C點(diǎn)對(duì)應(yīng)的測(cè)量x_C值和計(jì)算速度v_C值填在下表中的相應(yīng)位置．                                                                   

計(jì)數(shù)點(diǎn)        x/cm           s/cm           v/（m•s^﹣1）

O                1.00                              0.30

A                2.34            1.34            0.38

B                4.04            3.04            0.46

C                　 　          5.00            　 　

D                8.33            7.33            0.61

E                10.90          9.90            0.70

（3）實(shí)驗(yàn)小組通過(guò)繪制△v²﹣s圖線來(lái)分析運(yùn)動(dòng)規(guī)律（其中△v²=v²﹣v₀²，v是各計(jì)數(shù)點(diǎn)對(duì)應(yīng)時(shí)刻小車的瞬時(shí)速度，v₀是O點(diǎn)對(duì)應(yīng)時(shí)刻小車的瞬時(shí)速度）．他們根據(jù)實(shí)驗(yàn)數(shù)據(jù)在圖3中標(biāo)出了O、A、B、D、E對(duì)應(yīng)的坐標(biāo)點(diǎn)，請(qǐng)你在該圖中標(biāo)出計(jì)數(shù)點(diǎn)C對(duì)應(yīng)的坐標(biāo)點(diǎn)，并畫出△v²﹣s圖線．                                                                      

（4）實(shí)驗(yàn)小組繪制的△v²﹣s圖線的斜率k=                                          （用題中所給字母表示），若發(fā)現(xiàn)該斜率大于理論值，其原因可能是                                                                                  ．       

                                                                                                                                       

Answer 1

（1）（2）6.00，0.54

（3）如圖

（4）2，木板的左側(cè)墊的過(guò)高