挑战习题
1/5单选题
难度:

1.物体做匀速直线运动,拉力F=60牛,则物体受到的摩擦力是(  )
A 60牛
B 120牛
C 20牛
D 180牛
提示1:
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提示2:
IOaJgOS7pee7s+WtkOWvueeJqeS9k+eahOaLieWKm+W6lOivpeaYrzNG44CC
提示3:
IOeJqeS9k+WPl+WIsOWQkeW3pjNG55qE5ouJ5Yqb77yM5ZCR5Y+z55qE5pGp5pOm5Yqb77yM5ouJ5Yqb562J5LqO5pGp5pOm5Yqb44CC
正确答案:RA==
PGRpdj7niankvZPlj5fliLDlkJHlt6bnmoTmi4nlipszRuWSjOWQkeWPs+eahOaRqeaTpuWKm++8jOWboOS4uuebtOe6v+i/kOWKqO+8jOWQiOWKm+S4uumbtu+8jDNGPWY8L2Rpdj4=