00:01
Okay, in this problem we have an exercise room with six weightlifting machines that have no motors.
00:08
And seven treadmails with two and a half horsepower shaft output motors.
00:13
The motors operate at an average load factor of .7 and their efficiency is .77.
00:20
During peak eating hours, all 12, or i'm assuming this is supposed to be 13.
00:26
Pieces of equipment are used and there are two people doing exercise while waiting in line.
00:32
So we assume the average rate of heat dissipation from one person is 600 watts.
00:38
So i want to determine the rate of heat gain of the exercise room from people and equipment during peak load conditions.
00:51
Okay.
00:53
So for this problem, what we want to do is just look at all of the heat that's going into the system or all the energy actually that's going into the system, and the rate at which the energy is going in, and that will tell us the average rate of heat gain, or the rate of heat gain.
01:20
Okay, so we can say the rate at which the people are dissipating heat is equal to 600 watts, right? and we're assuming the room is sealed and insulated or whatever, right? so no heat is going to escape.
01:46
So we have an insulated system.
01:49
So let's say this is our system.
01:52
You know, we got the couple machines and we got all the machines and we got all these people, right? and we're going to take this room to be our system.
02:05
So we're assuming no heat is crossing this boundary, but we do have electrical power coming in for to power these.
02:15
Treadmails, right? so that's the only sort of work crossing the boundary.
02:20
Okay, so we have the rate at which the people are dissipating heat.
02:29
And then we also have the rate at which the motors are dissipating heat.
02:42
Okay, so this one is a little bit tricky because each motor has an output of 2 .5 horsepower.
02:56
So 2 .5 horsepower.
02:58
And then we're going to convert this.
02:59
So 1 horsepower is 745 .7 watts...