Question

两个大小相等的共点力F₁和F₂，当它们夹角为90°时，合力为F，当它们的夹角为120°时，合力大小为

A. 2F                                                           B. F

C.F                                                              D.

Answer 1

解析：F₁、F₂夹角为90°时，合力F＝F₁＝F₂，即F₁＝F₂＝F.当它们夹角为120°时，合力F′＝F₁＝F₂＝F，所以选项D正确.

答案：D