A 193 kg curtain needs to e raised 7.5 m, at constant speed, in as close to 5.0 s as possible. The power ratings for three motors are listed as 1.0 kW, 3.5 kW, and 5.5 kW. Which motor is best for the job?

best motor for above purpose is 3.5 kW

Explanation:

As we know that power is defined as the rate of work done

Here we have to raise the curtain so work is done against gravity

So we have

W = mgH

here we know

m = 193 kg

Now we have

now power used in it

So best motor for above purpose is 3.5 kW

i'm on my way to history not a mistory.