题目内容
(1)在这一过程中电动机要消耗的电能E1;
(2)一袋水泥机械能的增加量E2;
(3)摩擦所产生热量Q;
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154026311934.gif)
(1)
(2)
(3) ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154026772399.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824115402646520.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154026621474.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154026772399.jpg)
(1)解:E1= Pt ( 2分)
(2)解:E2 =
(2分)
(3)解:Q =Ff ΔS ① (2分) Ff= μmg cosθ ② (2分)
ΔS=S1-S2 ③ (2分)
S1为传送带运动的距离 S2为水泥袋运动距离S1=v t′ ④
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154027094650.jpg)
把②③④⑤⑥⑦式代入①式 解得Q=
(2分)
(2)解:E2 =
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154026621474.jpg)
(3)解:Q =Ff ΔS ① (2分) Ff= μmg cosθ ② (2分)
ΔS=S1-S2 ③ (2分)
S1为传送带运动的距离 S2为水泥袋运动距离S1=v t′ ④
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154027094650.jpg)
把②③④⑤⑥⑦式代入①式 解得Q=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241154026772399.jpg)
![](http://thumb2018.1010pic.com/images/loading.gif)
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