Help with physics test question please?
Question by Samantha: Help with physics test question please?
Also list these from highest to lowest cost to operate:
A. 1500 watt hair dryer for 10 mins.
B. 100 watt light bulb for 3 hours
C. 500 watt street light for 8 hours
D. 1000 watt microwave for 9 mins
E. 450 watt computer for 12 hours
Best answer:
Answer by dawgdays
What you want to determine is the total watt-hours for each part of the problem, and choose the highest. To do this, you multiple the wattage by the number of hours. Note that for a couple of these, the time is specified in minutes, so you have to convert those to equivalent hours. (Or I guess you could convert the hours to minutes, and calculate watt-minutes, but whatever.)
It’s probably the computer, but I haven’t done the computations, so you’ll want to double-check.
What do you think? Answer below!
If you make all the hours into minutes you could just multiply(i suck at english) them with the watt and then just from highest number to lowest number
November 4th, 2012 at 1:29 amWork = Power * time:
W = P * t
Determining the work (energy) for each example gives:
A. 1500 W * 1/6 h = 250 Wh
B. 100 W * 3 h = 300 Wh
C. 500 W * 3 h = 1500 Wh
D. 1000 W * 9/60 h = 150 Wh
E. 450 W * 12 h = 5400 Wh
So their ordering, from high cost to low cost, is: E, C, B, A, D
November 4th, 2012 at 2:18 am