Nobodyknows
New member
...(I am pulling my hair out)? The problem states: Suppose that 2 J of work is needed to stretch a spring from its natural length of 30 cm to a length of 42 cm.
(a) How much work is needed to stretch the spring from 35 cm to 40 cm?
The answer key is set up as follows:
If ? from 0 to 0.12 of kx dx = 2 J, then 2 = [1/2kx^2] from 0 to 0.12
0.12 meters that is
.....continued: = 1/2k(0.0144) = 0.0072k and k = 2/0.0072 = 2500/9 = about 277.78 N/m
NEWTON/METER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
WHY THE HELLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!?????????????????????????????????????
DAMN!!!!!!!!!!!!!!!!!!!
WHY?????
WHY?????????????????
Your damned work was defined in terms of joules and your distance in meters, so how the hell do you get N/m or (kg*m/s^2)/(m)?
How does anything in joules lead to kilograms and seconds and thus Newtons??????
What is the book making UP this time???
The answer should be in joules/meter instead of N/m as I am looking at it.
We then do this:
? from 0.05 to 0.10 of (2500/9)x dx
integrate and you get something in J joules.
How?
(a) How much work is needed to stretch the spring from 35 cm to 40 cm?
The answer key is set up as follows:
If ? from 0 to 0.12 of kx dx = 2 J, then 2 = [1/2kx^2] from 0 to 0.12
0.12 meters that is
.....continued: = 1/2k(0.0144) = 0.0072k and k = 2/0.0072 = 2500/9 = about 277.78 N/m
NEWTON/METER!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
WHY THE HELLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!?????????????????????????????????????
DAMN!!!!!!!!!!!!!!!!!!!
WHY?????
WHY?????????????????
Your damned work was defined in terms of joules and your distance in meters, so how the hell do you get N/m or (kg*m/s^2)/(m)?
How does anything in joules lead to kilograms and seconds and thus Newtons??????
What is the book making UP this time???
The answer should be in joules/meter instead of N/m as I am looking at it.
We then do this:
? from 0.05 to 0.10 of (2500/9)x dx
integrate and you get something in J joules.
How?