2.1 2 3 4 题物理帮一帮

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2.1 2 3 4 题物理帮一帮
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2.1 2 3 4 题物理帮一帮
2.1 2 3 4 题物理帮一帮
 

2.1 2 3 4 题物理帮一帮
1、W有用=G*s=630N*3m=1890J
2、W总=F*3s=300N*9m=2700J
3、效率n=W有用/W总=1890J/2700J=70%
4、P=W总/t=2700J/4s=675w

(1) W有 = 630N * 3m = 1890J
(2) W总 = 300N * 3m * 3 = 2700J
(3) η = 1890/2700 * 100% = 70%
(4) P = 2700J / 4s = 675W