Question

4．甲乙兩隊(duì)進(jìn)行拔河比賽，甲隊(duì)勝乙隊(duì)負(fù)，則下列說法正確的是（　�。�

• A． 甲隊(duì)對(duì)乙隊(duì)的拉力大于乙隊(duì)對(duì)甲隊(duì)的拉力
• B． 甲隊(duì)對(duì)乙隊(duì)的拉力與地面對(duì)乙隊(duì)的摩擦力大小相等，它們是一對(duì)平衡力
• C． 甲隊(duì)對(duì)乙隊(duì)的拉力與乙隊(duì)對(duì)甲隊(duì)的拉力是一對(duì)平衡力
• D． 甲隊(duì)對(duì)乙隊(duì)的拉力與乙隊(duì)對(duì)甲隊(duì)的拉力大小相等，它們是一對(duì)作用力和反作用力

Answer 1

分析 作用力和反作用力一定是兩個(gè)物體之間的相互作用力，并且大小相等，方向相反，同時(shí)產(chǎn)生同時(shí)消失，而平衡力作用在同一個(gè)物體上，不一定會(huì)同時(shí)產(chǎn)生和消失．

解答 解：A、C、D、甲對(duì)乙的拉力與乙對(duì)甲的拉力是作用力和反作用力，大小相等，故AC錯(cuò)誤，D正確；
B、甲隊(duì)勝乙隊(duì)負(fù)，則甲隊(duì)對(duì)乙隊(duì)的拉力大于地面對(duì)乙隊(duì)的摩擦力，故B錯(cuò)誤．
故選：D

點(diǎn)評(píng) 此題通過一種拔河比賽，考查了平衡力與相互作用力的區(qū)別，特別是A選項(xiàng)，很容易出錯(cuò)．