问题
选择题
质量为m的物体静止在粗糙的水平面上,当此物体受水平力F作用运动距离S时,动能为Ek1,而当此物体受水平力2F作用相同的距离时,其动能为Ek2,则( )
A.Ek2=Ek1
B.Ek2=2Ek1
C.Ek2>2Ek1
D.Ek1<Ek2<2Ek1
答案
由动能定理可得:
FS-Wf=EK1----(1)
2F作用时,由动能定理可得:
2FS-Wf=EK2----(2)
将(1)式乘以2可得:
2FS-2Wf=2EK1,
则可得出EK2>2EK1;
故选C.