物体的最大静摩擦力为f=μmg=2N A、在0-1s内,拉力小于最大静摩擦力,物体静止,1-2s内,a==1m/s2,位移x1=at2=×1×1m=0.5m,v1=at=1m/s; 2-3s内,a==3m/s2,位移x2=v1t+at2=1×1+×3×1m=2.5m,所以总位移为0.5+2.5m=3m; B、在0-1s内,a==1m/s2,位移x1=at2=×1×1m=0.5m,v1=at=1m/s;1-2s内,a==-1m/s2, 位移x2=v1t+at2=1×1-×1×1m=0.5m,v2=v1+a1t=1-1=0;2-3s内,a==3m/s2,位移x3=at2=×3×1m=1.5m, 总位移为:0.5+0.5+1.5m=2.5m; C、在0-1s内,拉力小于最大静摩擦力,物体静止,1-2s内,a==3m/s2,位移x1=at2=×3×1m=1.5m,v1=at=3m/s;2-3s内, a==1m/s2,位移x2=v1t+at2=3×1+×1×1m=3.5m,总位移为:1.5+3.5m=5m; D、在0-1s内,a==3m/s2,位移x1=at2=×3×1m=1.5m,v1=at=3m/s;1-2s内, a==1m/s2,位移x2=v1t+at2=3×1+×1×1m=3.5m,v2=v1+at=3+1m/s=4m/s;2-3s内,a==-1m/s2, 位移x3=v2t+at2=4×1-×1×1m=3.5m,总位移为:1.5+3.5+3.5m=8.5m; 所以D发生的位移最大. 故选D |