Question

已知力F使質(zhì)量為m的物體從靜止開始在t時(shí)間內(nèi)運(yùn)動(dòng)了位移為s，則下列說法中正確的是（ ）
A．相同的力F可以使質(zhì)量為的物體從靜止開始在t時(shí)間內(nèi)運(yùn)動(dòng)了位移為s
B．相同的力可使質(zhì)量為2m的物體從靜止開始在2t時(shí)間內(nèi)運(yùn)動(dòng)了位移為s
C．F的力可使質(zhì)量為的物體從靜止開始在t時(shí)間內(nèi)運(yùn)動(dòng)了位移為s
D．F的力可使質(zhì)量為m的物體從靜止開始在t時(shí)間內(nèi)運(yùn)動(dòng)了位移為s

Answer 1

【答案】分析：根據(jù)牛頓第二定律求出物體的加速度，根據(jù)運(yùn)動(dòng)學(xué)公式求出位移．
解答：解：A、根據(jù)牛頓第二定律，a=，質(zhì)量變?yōu)樵瓉淼?img src="http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191714006077077/SYS201310291917140060770002_DA/1.png">，加速度變?yōu)樵瓉淼?倍，根據(jù)，時(shí)間變?yōu)樵瓉淼囊话�，則位移變?yōu)樵瓉淼囊话耄�故A錯(cuò)誤．
   B、根據(jù)牛頓第二定律，a=，質(zhì)量變?yōu)樵瓉淼?倍，加速度變?yōu)樵瓉淼?img src="http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191714006077077/SYS201310291917140060770002_DA/4.png">倍，根據(jù)，時(shí)間變?yōu)樵瓉淼?倍，則位移變?yōu)樵瓉淼?倍．故B錯(cuò)誤．
   C、根據(jù)牛頓第二定律，a=，力變?yōu)樵瓉淼?img src="http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191714006077077/SYS201310291917140060770002_DA/7.png">，質(zhì)量變?yōu)樵瓉淼?img src="http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191714006077077/SYS201310291917140060770002_DA/8.png">，加速度不變，根據(jù)，時(shí)間不變，則位移不變．故C錯(cuò)誤．
D、根據(jù)牛頓第二定律，a=，力變?yōu)樵瓉淼?img src="http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191714006077077/SYS201310291917140060770002_DA/11.png">，質(zhì)量變?yōu)樵瓉淼?img src="http://thumb.1010pic.com/pic6/res/gzwl/web/STSource/20131029191714006077077/SYS201310291917140060770002_DA/12.png">，加速度不變，根據(jù)，時(shí)間不變，則位移不變．故D正確．
故選D．
點(diǎn)評(píng)：加速度是聯(lián)系力學(xué)和運(yùn)動(dòng)學(xué)的橋梁，通過加速度，根據(jù)力可以求運(yùn)動(dòng)，也可以根據(jù)運(yùn)動(dòng)求力．