位于水平面上的物体,在与水平方向成θ角的斜向下的恒力F1作用下,做速度为v1的匀

题型:选择题

问题:

位于水平面上的物体,在与水平方向成θ角的斜向下的恒力F1作用下,做速度为v1的匀速运动;若作用力变为与水平方向成θ角的斜向上的恒力F2,物体做速度为v2的匀速运动,且F1与F2功率相同,则可能有(  )

A.F1=F2,v1>v2

B.F1=F2,v1<v2

C.F1>F2,v1<v2

D.F1<F2,v1>v2

考点:滑动摩擦力、动摩擦因数力的合成共点力的平衡平均功率和瞬时功率的区别
题型:选择题

Miss Green was very fat. She weighed 100 kilos, and she was getting heavier every month, so she went to see her doctor.The doctor said, ‘‘You need a diet(节食), Miss Green, and I’ve got a good one here.” He gave her a small book and said, ‘Read this carefully and eat the things listed on page 11 every day. Then come back and see me in two weeks’ time.’

Miss Green came again two weeks later, but she wasn’t thinner, she was fatter. The doctor was surprised and said, ‘‘ Are you eating the things listed on page 11 of the small book?”

  ‘‘Yes, doctor,’’ she answered.

  The next day the doctor visited Miss Green during her dinner. She was very surprised to see him.

  ‘‘ Miss Green,’’ he said, ‘‘why aren’t you eating salad? Why are you eating potatoes and bread? They aren’t in your diet.’’

  ‘‘But, doctor,’’ Miss Green answered. ‘‘I ate my diet at lunch time. This is my dinner’’

阅读短文内容,判断正(T)误(F)

小题1:Miss Green was getting fatter every month.

小题2:Miss Green didn’t feel well,so she went to see a doctor.

小题3:Two weeks later,Miss Green was thinner.

小题4:The diet is on page11.

小题5:Miss Green didn’t understand the doctor’s advice.   

题型:选择题

康明斯发电车中燃油泵是利用()电源工作的。

A.DC24V

B.DC48V

C.本车用电

D.I、II路干线

题型:选择题

我国发射了一颗亚洲一号同步通信卫星,如果已知地球半径为R,地球自转角速度为ω,地球表面重力加速度为g,则下列哪些物理量可以求出(     )

A.卫星受到的地球引力

B.卫星在轨道上运行的加速度

C.卫星在轨道上运行的线速度

D.卫星离地面的高度

题型:选择题

我国北京周口店发现的“北京猿人”属于[ ]

A.智人

B.直立人

C.能人

D.南方古猿

题型:选择题

防火巡查人员应该及时纠正违章行为,妥善处置火灾危险,无法当场处置的,应当()。

(A)立即强制执行

(B)记录备案

(C)立即报告

(D)保持现状,以后再说

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