How long will it take a 1750W motor to lift 315-kg piano sixth story window 16m above?

```

Work = Force x Distance

```

In this case, the force is the weight of the piano, which is:

```

Force = mass x gravity

Force = 315 kg x 9.8 m/s²

Force = 3087 N

```

The distance is the height the piano needs to be lifted, which is 16 m.

```

Work = 3087 N x 16 m

Work = 49,408 J

```

The power of the motor is 1750 W, which means that it can do 1750 J of work per second.

```

Time = Work / Power

Time = 49,408 J / 1750 W

Time = 28.23 s

```

Therefore, it will take the motor 28.23 seconds to lift the piano to the sixth-story window.