Fill in the empty columns of a work/power table

AI Thread Summary
The discussion revolves around filling in the empty columns of a work/power table for a homework assignment. The user has successfully completed some rows but is struggling with the last two columns, particularly regarding the estimated hours of use per week. It is clarified that the hours of use are not fixed and can be assumed based on reasonable usage patterns, as the problem is a practice question. The confusion stems from the expectation that estimated time should be provided in the table, but it is ultimately up to the user to decide. The conversation emphasizes the need for assumptions when solving such problems.
ElegantSir
Messages
37
Reaction score
0

Homework Statement


"Fill in the empty columns of the following table"

Table is in the thumbnail

Homework Equations


work = force / distance
power = work / time

Y = E * c
-Y is the yearly running cost
-E is the EnerGuide energy rating per year
-c is the cost of electricity per kW/h


The Attempt at a Solution


I have already filled in the first 2 blank rows on the table.
The E per week is 5.08kWh/week and 17.5kWh/week
for the running yearly cost Y it is $0.30/week and $1.05/week

This is where I am stuck. I have no idea how to fill out the last 2 columns with the information I currently have. I thought I would need to divide and or multiply a number by 168 (number of hours in a week) but that doesn't seem to do any good. Could someone point me in the direction as to what I need to calculate in order to find the estimated hours of use per week?
 

Attachments

  • Untitled.png
    Untitled.png
    39.1 KB · Views: 741
Physics news on Phys.org
It just depends on your choice :)
 
Daeho Ro said:
It just depends on your choice :)
Does that mean that the time is completely up to you to decide? The only reason I am confused about this is because this is only a practice question and the actual homework has a table almost identical to this one where it asks the "estimated hours of use."
So to reiterate the hours of use I am supposed to be making up..?
 
Yes, it seems. Sometimes you have to give some condition to solve an problem. Usually, people didn't watch the TV whole 7 days :)
 
Daeho Ro said:
Yes, it seems. Sometimes you have to give some condition to solve an problem. Usually, people didn't watch the TV whole 7 days :)
Hmm, it makes sense. But you would think that if I wasnt supposed to solve something that the estimated time would be an automatic given variable on the table.
 
I read carefully the problem, but I didn't get it.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top