如图所示,工人用200N的拉力,在15s的时间内,将重500N的建筑材料提升到6m高的楼顶上,求:
1个回答

解题思路:

(1)读题并观图可知:

F

=

200

N

s

=

3

h

=

3

×

6

m

=

18

m

W

=

F

s

=

200

N

×

18

m

=

3.6

×

10

3

J

(2)

G

=

500

N

h

=

6

m

W

=

G

h

=

500

N

×

6

m

=

3

×

10

3

J

(3)当不计绳与滑轮组间的摩擦及绳重时,

(

G

+

G

)

=

"

3

F

"

G

=

"

3

F

"

G

=

3

×

200

N

500

N

=

100

N

.

(1)3.6×10 3J (2)83.3% (3)  100N

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