{"code":0,"msg":"success","data":[[{"head_title":"实验探究题","questions":[{"question_id":"1456268","question_type":"7","question_channel_type":"26","is_explain":"1","is_on_sale":"1","question_status":"2","chid":"5","xd":"2","parent_id":"0","is_objective":"0","difficult_index":"3","master_level":"2","exam_type":"2","evaluated":"0","region_ids":"","grade_id":"7","question_source":"","mode":"2","title":"某课外兴趣小组的同学们为研究蜗牛的运动情况,将蜗牛放在刻度尺上让其沿刻度尺爬行,并每隔l0秒拍摄记录蜗牛的位置,拍成如图所示的图片。...","kid_num":"1","paperid":"0","save_num":"98","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"
某课外兴趣小组的同学们为研究蜗牛的运动情况,将蜗牛放在刻度尺上让其沿刻度尺爬行,并每隔l0秒拍摄记录蜗牛的位置,拍成如图所示的图片。
同学们依据此图片获得数据,如下表:
照片序号 | 1 | 2 | 3 | 4 | 5 | 6 |
时间t/s | 0 | 10 | 20 | 30 | 40 | 50 |
路程s/mm | 0 | 12.0 | 22.2 | 44.0 | 58.9 |
在探究“滑动摩擦力的大小与哪些因素有关”的实验中,同学们提出了以下猜想:
A.与压力大小有关 B.与接触面的粗糙程度有关
C.与接触面积大小有关 D.与运动速度大小有关
为了验证以上猜想是否正确,小张组的同学利用如图所示装置及有关器材进行实验,收集的数据如下表:
序号 | 长方体木块的放置 | 表面情况 | 压力/N | 测力计示数/N |
1 | 平放 | 木板 | 5 | 1.2 |
2 | 平放 | 木板 | 8 | 1.9 |
3 | 侧放 | 木板 | 5 | 1.2 |
4 | 平放 | 木板上铺毛巾 | 5 | 2.0 |
步骤一:将铁块放在木板上,往沙桶中加入一定量细沙,使压力传感器的示数为5.00牛,水平向左拉动木板,读出拉力传感器的示数并记录。
步骤二:换用质量不同、粗糙程度和底面积都相同的铁块,重复步骤一,记录结果如下表。
请回答下列问题:
","options":"","sub_explanation":null,"list":[{"question_id":"44545767","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2017-09-30 00:00:00","update_by":"","update_uid":"0","update_date":"2024-01-25 00:33:59","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"5197955","sort":7,"is_objective":"0","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"第1次实验中铁块受到的摩擦力为牛。","options":"","answer":"[\"2.10\"]","answer_json":["2.10"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":1},{"question_id":"44545771","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2017-09-30 00:00:00","update_by":"","update_uid":"0","update_date":"2024-01-25 00:33:59","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"5197955","sort":8,"is_objective":"1","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"实验中能否用钩码代替细沙?并说明理由。","options":"","answer":"[\"\\u4e0d\\u80fd\\uff1b\\u7ec6\\u6c99\\u8d28\\u91cf\\u5c0f\\uff0c\\u80fd\\u8f83\\u4e3a\\u51c6\\u786e\\u7684\\u8c03\\u8282\\u5bf9\\u94c1\\u5757\\u7684\\u62c9\\u529b\\uff0c\\u6765\\u4fdd\\u8bc1\\u538b\\u529b\\u5927\\u5c0f\\u76f8\\u540c\"]","answer_json":["不能;细沙质量小,能较为准确的调节对铁块的拉力,来保证压力大小相同"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":2},{"question_id":"44545773","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2017-09-30 00:00:00","update_by":"","update_uid":"0","update_date":"2024-01-25 00:33:59","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"5197955","sort":9,"is_objective":"1","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"通过实验得出的结论是。","options":"","answer":"[\"\\u6469\\u64e6\\u529b\\u5927\\u5c0f\\u4e0e\\u91cd\\u529b\\u65e0\\u5173\"]","answer_json":["摩擦力大小与重力无关"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":3},{"question_id":"44545775","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2017-09-30 00:00:00","update_by":"","update_uid":"0","update_date":"2024-01-25 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","options":"","sub_explanation":null,"list":[{"question_id":"39041698","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2016-05-23 05:07:19","update_by":"","update_uid":"0","update_date":"2024-01-26 10:46:37","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"2405651","sort":11,"is_objective":"0","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"当卡片静止时,发现拉线不在同一直线上(如图甲所示),于是他得出:二力平衡时,两个力可以不在同一直线上,你认为造成这种情况的原因是,要得到科学的结论,请你给他提出一条改进建议是:;","options":"","answer":"[\"\\u5361\\u7247\\u6709\\u91cd\\u529b\",\"\\u9009\\u8f7b\\u8d28\\u5361\\u7247(\\u6216\\u589e\\u5927\\u5bf9\\u5361\\u7247\\u7684\\u62c9\\u529b)\"]","answer_json":["卡片有重力","选轻质卡片(或增大对卡片的拉力)"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":"","2":""},"sort2":1},{"question_id":"39041700","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2016-05-23 05:07:19","update_by":"","update_uid":"0","update_date":"2024-01-26 10:46:37","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"2405651","sort":12,"is_objective":"0","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"实验改进后出现了如图乙所示平衡现象,若使卡片在图示位置失去平衡,你将通过或方法实现。","options":"","answer":"[\"\\u5bf9\\u5361\\u7247\\u4e24\\u7aef\\u65bd\\u52a0\\u4e0d\\u540c\\u7684\\u62c9\\u529b\",\"\\u4f7f\\u4e24\\u62c9\\u529b\\u4e0d\\u5728\\u540c\\u4e00\\u76f4\\u7ebf\\u4e0a(\\u6216\\u5c06\\u5361\\u7247\\u526a\\u6210\\u4e24\\u5757)\"]","answer_json":["对卡片两端施加不同的拉力","使两拉力不在同一直线上(或将卡片剪成两块)"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":"","2":""},"sort2":2}],"knowledge":null,"category":null,"is_collect":false,"done":false,"myanswer":"","score":{"score":"4","subScore":["2","2"]},"sort":11,"sort2":4,"is_use":0},{"question_id":"3680278","question_type":"7","question_channel_type":"26","is_explain":"1","is_on_sale":"1","question_status":"2","chid":"5","xd":"2","parent_id":"0","is_objective":"0","difficult_index":"3","master_level":"2","exam_type":"7","evaluated":"0","region_ids":"11","grade_id":"9","question_source":"浙江省嘉兴市十校2017届九年级下学期4月联合模拟科学试卷","mode":"2","title":"实验小组的同学用如图所示的装置探究“物体动能大小与质量和速度的关系”。放在斜面上某一高度处的小钢球A滚下时,撞击水平面上木块B,并将...","kid_num":"1","paperid":"162950","save_num":"156","oldqid":"0","explain_sort_need":"0","paper":{"pid":"162950","title":"浙江省嘉兴市十校2017届九年级下学期4月联合模拟科学试卷"},"extra_file":"","question_text":"实验小组的同学用如图所示的装置探究“物体动能大小与质量和速度的关系”。放在斜面上某一高度处的小钢球A滚下时,撞击水平面上木块B,并将木块B推出一段距离,数据记录如表所示。
实验 次数 | 钢球 质量/g | 钢球高度/cm | 木块滑行距离/cm |
1 | 20 | 20 | 30 |
2 | 40 | 20 | 58 |
3 | 60 | 20 | 75 |
\n\n","kid_num":"1","paperid":"246506","save_num":"79","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"在探究“力对物体运动的影响”的实验中,在水平桌面上分别铺上粗糙程度不同的毛巾、棉布、木板,让同一小车从斜面同一位置由静止开始滑下,小车滑下后,在不同物体表面上运动的距离如图所示: ","options":"","sub_explanation":null,"list":[{"question_id":"38119228","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2017-05-10 10:20:38","update_by":"","update_uid":"0","update_date":"2024-01-25 04:08:21","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"4630982","sort":15,"is_objective":"1","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"实验时让同一小车每次都从斜面同一位置由静止开始滑下,是为了让小车到达水平面时的速度.","options":"","answer":"[\"\\u76f8\\u540c\"]","answer_json":["相同"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":1},{"question_id":"38119230","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2017-05-10 10:20:38","update_by":"","update_uid":"0","update_date":"2024-01-25 04:08:21","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"4630982","sort":16,"is_objective":"1","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"由图可知,小车在木板上运动的距离最远,这说明,接触面越光滑,小车受到的阻力越,速度减小得越慢.","options":"","answer":"[\"\\u5c0f\"]","answer_json":["小"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":2},{"question_id":"38119232","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"风中的驻足1992","create_uid":"6898401","create_date":"2017-05-10 10:20:38","update_by":"","update_uid":"0","update_date":"2024-01-25 04:08:21","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"4630982","sort":17,"is_objective":"1","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"根据这个实验推理:若水平物体表面绝对光滑(即小车不受任何阻力作用),那么小车将.","options":"","answer":"[\"\\u505a\\u5300\\u901f\\u76f4\\u7ebf\\u8fd0\\u52a8\"]","answer_json":["做匀速直线运动"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":3}],"knowledge":null,"category":null,"is_collect":false,"done":false,"myanswer":"","score":{"score":"3","subScore":["1","1","1"]},"sort":15,"sort2":6,"is_use":0}],"scores":{"1456268":{"score":"3","subScore":["1","2"]},"2095491":{"score":"6","subScore":["2","2","1","1"]},"2405651":{"score":"4","subScore":["2","2"]},"3680278":{"score":"2","subScore":["1","1"]},"4630982":{"score":"3","subScore":["1","1","1"]},"5197955":{"score":"4","subScore":["1","1","1","1"]}},"sum_score":22,"question_num":6},{"head_title":"综合题","questions":[{"question_id":"2351429","question_type":"7","question_channel_type":"4","is_explain":"1","is_on_sale":"1","question_status":"2","chid":"5","xd":"2","parent_id":"0","is_objective":"0","difficult_index":"3","master_level":"2","exam_type":"2","evaluated":"0","region_ids":"11","grade_id":"7","question_source":"浙教版科学七年级下册第三章第3节重力练习","mode":"2","title":"小明做探究物体所受重力大小与物体质量的关系的实验,实验数据记录如下表。质量(千克)重力(牛)比值(G/m)(牛/千克)比值平均值(牛/千克)0.100...","kid_num":"4","paperid":"29999","save_num":"187","oldqid":"0","explain_sort_need":"0","paper":{"pid":"29999","title":"浙教版科学七年级下册第三章第3节重力练习"},"extra_file":"","question_text":"小明做探究物体所受重力大小与物体质量的关系的实验,实验数据记录如下表。
质量(千克) | 重力(牛) | 比值(G/m)(牛/千克) | 比值平均值(牛/千克) |
0.10 | 0.99 | 9.9 | (2) |
0.20 | 1.96 | (1) | |
0.30 | 2.91 | 9.7 |
地点 | g值的大小 | 纬度 |
赤道 | 9.780 | 0° |
广州 | 9.788 | 23°06′ |
武汉 | 9.794 | 30°33′ |
上海 | 9.794 | 31°12′ |
北京 | 9.801 | 39°56′ |
纽约 | 9.803 | 40°40′ |
莫斯科 | 9.816 | 55°45′ |
北极 | 9.832 | 90° |
通过分析上表,可以发现,g值相同的城市是;g值相差最大的两个 地区是。试猜想g值变化的原因可能是。
","options":"","answer":"[\"\\u6b66\\u6c49\\u548c\\u4e0a\\u6d77\",\"\\u5317\\u6781\\u548c\\u8d64\\u9053\",\"\\u7eac\\u5ea6\\u53d8\\u5316\"]","answer_json":["武汉和上海","北极和赤道","纬度变化"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":"","2":"","3":""},"sort2":4},{"question_id":"39058774","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"huiqiner","create_uid":"6966711","create_date":"2016-05-11 10:08:35","update_by":"","update_uid":"0","update_date":"2021-07-01 17:35:36","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"2351429","sort":22,"is_objective":"1","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"实验后,小明还想进一步探究物体受到的重力大小与物体体积的关系,请你设计一个实验方案(简述实验步骤): ;","options":"","answer":"[\"\\u5206\\u522b\\u6d4b\\u51fa\\u8d28\\u91cf\\u76f8\\u540c\\u7684\\u4e24\\u4e2a\\u7269\\u4f53\\u7684\\u4f53\\u79ef\\uff08\\u4e0d\\u540c\\uff09\\uff0c\\u7136\\u540e\\u7528\\u5f39\\u7c27\\u6d4b\\u529b\\u8ba1\\u5206\\u522b\\u6d4b\\u51fa\\u8fd9\\u4e24\\u4e2a\\u7269\\u4f53\\u7684\\u91cd\\u529b\\uff0c\\u518d\\u8fdb\\u884c\\u6bd4\\u8f83\\u3002\"]","answer_json":["分别测出质量相同的两个物体的体积(不同),然后用弹簧测力计分别测出这两个物体的重力,再进行比较。"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":5}],"knowledge":null,"category":null,"is_collect":false,"done":false,"myanswer":"","score":{"score":"9","subScore":["2","2","1","3","1"]},"sort":18,"sort2":7,"is_use":0},{"question_id":"2097264","question_type":"7","question_channel_type":"26","is_explain":"1","is_on_sale":"1","question_status":"2","chid":"5","xd":"2","parent_id":"0","is_objective":"0","difficult_index":"3","master_level":"2","exam_type":"2","evaluated":"0","region_ids":"11","grade_id":"8","question_source":"","mode":"2","title":" 小王同学用下列器材研究“影响滑动摩擦力大小的因素”:粗糙程度均匀的长木板一块,质量相等的木块和铝块各一个,弹簧测力计一只.如图所...","kid_num":"1","paperid":"0","save_num":"38","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"小王同学用下列器材研究“影响滑动摩擦力大小的因素”:粗糙程度均匀的长木板一块,质量相等的木块和铝块各一个,弹簧测力计一只.如图所示,4次实验中他都用弹簧测力计沿水平方向缓慢拉动物块,使其在水平长木板上做匀速直线运动.
","options":"","sub_explanation":null,"list":[{"question_id":"39110494","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"信息化时代","create_uid":"6838503","create_date":"2016-01-28 10:25:44","update_by":"","update_uid":"0","update_date":"2024-01-26 13:50:28","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"2097264","sort":23,"is_objective":"0","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"图丙中,弹簧测力计示数为 N,铝块受到的摩擦力大小为 N.","options":"","answer":"[\"3.2\",\"0\"]","answer_json":["3.2","0"],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":"","2":""},"sort2":1},{"question_id":"39110496","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"信息化时代","create_uid":"6838503","create_date":"2016-01-28 10:25:44","update_by":"","update_uid":"0","update_date":"2024-01-26 13:50:28","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"2097264","sort":24,"is_objective":"1","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"分析 两次实验,可得出:在接触面粗糙程度相同时,滑动摩擦力大小与压力有关.","options":"","answer":"[\"\\u7532\\u3001\\u4e19\\u3000\"]","answer_json":["甲、丙 "],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":2},{"question_id":"39110498","qsn_id":null,"question_type":"4","question_channel_type":"0","is_explain":"0","is_on_sale":"0","question_status":"0","question_tags":"","chid":"5","xd":"2","create_by":"信息化时代","create_uid":"6838503","create_date":"2016-01-28 10:25:44","update_by":"","update_uid":"0","update_date":"2024-01-26 13:50:28","update_reason":"","audit_by":"","audit_uid":"0","audit_date":null,"audit2_by":"","audit2_uid":"0","audit2_date":null,"opinion":null,"parent_id":"2097264","sort":25,"is_objective":"1","difficult_index":"0","master_level":"0","exam_type":"0","evaluated":"0","region_ids":"","grade_id":"0","question_source":"","mode":"2","is_delete":"0","md5sum":"","title":"","kid_num":"0","paperid":"0","save_num":"0","oldqid":"0","explain_sort_need":"0","paper":null,"extra_file":"","question_text":"图乙与图丁中铝块受到的摩擦力大小 .(选填“相等”、“不相等”或“不确定”)","options":"","answer":"[\"\\u76f8\\u7b49\\u3000\"]","answer_json":["相等 "],"explanation":"","pic_answer":"0","pic_explanation":"0","sub_explanation":null,"knowledge":null,"category":null,"done":false,"myanswer":{"1":""},"sort2":3}],"knowledge":null,"category":null,"is_collect":false,"done":false,"myanswer":"","score":{"score":"4","subScore":["2","1","1"]},"sort":23,"sort2":8,"is_use":0},{"question_id":"2815152","question_type":"7","question_channel_type":"26","is_explain":"1","is_on_sale":"1","question_status":"2","chid":"5","xd":"2","parent_id":"0","is_objective":"0","difficult_index":"5","master_level":"4","exam_type":"2","evaluated":"0","region_ids":"11","grade_id":"7","question_source":"浙教版科学七年级下学期期末质量检测模拟卷(A)","mode":"2","title":"小明发现,高空坠物下落越来越快,而跳伞远动员利用降落伞却能安全着地。空中下落的物体,其最大速度与什么因素有关呢?为了研究这一问题,...","kid_num":"2","paperid":"49462","save_num":"912","oldqid":"0","explain_sort_need":"0","paper":{"pid":"49462","title":"浙教版科学七年级下学期期末质量检测模拟卷(A)"},"extra_file":"","question_text":"小明发现,高空坠物下落越来越快,而跳伞远动员利用降落伞却能安全着地。空中下落的物体,其最大速度与什么因素有关呢?为了研究这一问题,小明在老师的帮助下进行如下实验:
①取相同型号、质量为m的纸杯10个,按如图所示分成A、B、C、D四组。
②将A组纸杯在一定高度、底部向下静止释放,让其自由下落,并用仪器记录下落过程中的速度。
③分别用B、C、D组纸杯重复步骤②。
④记录并整理相关数据如下表。
时间(秒) 速度(米/秒) 烧杯质量 | 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 |
m | 0.5 | 0.8 | 1.0 | 1.1 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 |
2m | 0.6 | 1.0 | 1.3 | 1.5 | 1.6 | 1.7 | 1.7 | 1.7 | 1.7 | 1.7 |
3m | 0.8 | 1.3 | 1.6 | 1.9 | 2.0 | 2.1 | 2.2 | 2.2 | 2.2 | 2.2 |
4m | 0.9 | 1.5 | 1.8 | 2.0 | 2.2 | 2.4 | 2.5 | 2.6 | 2.6 | 2.6 |
有一个风洞实验室,一架模型飞机固定在托盘测力计上如图所示.无风时,托盘测力计示数为15N;当迎面有风吹过时,托盘测力计的示数减小,可以判定飞机受到了一个新的力,我们把这个新的力称为 力,方向是 .
下面是某小组研究该力的大小与风速关系的实验数据:
风速/(m/s) | 5 | 10 | 15 | 20 | 25 | 30 | 35 |
托盘测力计的示数/N | 14.5 | 13.0 | 10.5 | 7.0 | 2.5 | 0 | 0 |
根据上面的实验数据可知:飞机受到的这个新的力大小随着风速的增大而 .由此推测,飞机短距离快速起飞时应该 (顺风.逆风)起飞.
当风速达到30m/s以上,托盘测力计的示数是0,说明了什么? .
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