Answer:
180,000
Explanation:
Frequency is a quantity that is measured in Hertz [Hz] and it represents the number of rotations per second.
A motor with a frequency of 50 Hz will rotate 50 times per second.
Since we don't want to know how many times it rotates per second, but per hour. The first step is to find how many seconds there are in an hour and then multiply that amount by 50.
Seconds in an hour:
there are 60 seconds per minute, and 60 minutes per hour, thus there are
60*60 = <u>3,600 seconds in an hour</u>
We know that the motor will rotate 50 times per second so to find the number of rotations in 1 hour = 3,600 seconds we multiply:
50*3,600 = 180,000 rotations
Answer:
The rate at which the container is losing water is 0.0006418 g/s.
Explanation:
- Under the assumption that the can is a closed system, the conservation law applied to the system would be: , where is all energy entering the system, is the total energy leaving the system and, is the change of energy of the system.
- As the purpose is to kept the beverage can at constant temperature, the change of energy () would be 0.
- The energy that goes into the system, is the heat transfer by radiation from the environment to the top and side surfaces of the can. This kind of transfer is described by: where is the emissivity of the surface, known as the Stefan–Boltzmann constant, is the total area of the exposed surface, is the temperature of the surface in Kelvin, is the environment temperature in Kelvin.
- For the can the surface area would be ta sum of the top and the sides. The area of the top would be , the area of the sides would be . Then the total area would be
- Then the radiation heat transferred to the can would be .
- The can would lost heat evaporating water, in this case would be , where is the rate of mass of water evaporated and, is the heat of vaporization of the water ().
- Then in the conservation balance: , it would be.
- Recall that , then solving for :
The first thing you should know for this case is that density is defined as the quotient between mass and volume:
D = M / V
In addition, you should keep in mind the following conversion:
1Kg = 1000g
Substituting the values we have:
D = (23.0 * 1000) / (2920) = 7.88 g / cm ^ 3
answer
the density of the iron plate is 7.88 g / cm ^ 3