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> 用400N的力在水平地面上拉车行走50m，拉力与车前进的方向成30°角。那么，拉力对车做的功是( ) A．2.0×104J B．1.0×104J C．1.7×104J D．以上均不对

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发布时间：2024-09-09

用400N的力在水平地面上拉车行走50m，拉力与车前进的方向成30°角。那么，拉力对车做的功是( )

A．2.0×10⁴J B．1.0×10⁴J C．1.7×10⁴J D．以上均不对

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