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### 11.10 Example 10

A box of 80 kg is rising to a crane, in 3 minutes, at the flat roof of a building of 50 meters. Which is the developed power to the crane?

Solution with FisicaLab

Erase the content of the chalkboard and select the SI system. And add one element Stationary reference system, one element Block with vertical movement, one element Force applied to the block, and one element Power. As show the image below: To the element Stationary reference system write:

g

9.81

t

3 @ min

To the block, we assume that this leave the rest and we call this Box, write:

Name

Box

m

80

a

a

vi

0

vf

vf

d

50

Relative to

sf

To the element Force:

f

f

To the element Power:

Object

Box

P

Power

Now click in the icon Solve to get the answer:

```
f = 785.047 N ;  a = 0.003 m/s2 ;  vf = 0.556 m/s ;
Power = 218.069 W ;
Status = success.

```

NOTE: You can also calculate the developed power when the box is rising with a constant velocity. To do this, write 0 in the acceleration, and initial velocity and final velocity as unknown data.