mayankdevnani
A steam engine has an efficiency of 20%.It is given an energy of 1000 cal.per minute.What is the actual work done by it in joule and in calories?
a) 100 cal,800 J
b) 200 cal,873 J
c)10 cal,80 J
d)100 cal,100 J
Delete
Share
This Question is Closed
mayankdevnani
Best Response
You've already chosen the best response.
1
@amistre64 @ParthKohli @hartnn @Callsito @Zarkon @Hero @.Sam. @estudier @ganeshie8 @ajprincess @Algebraic!
mayankdevnani
Best Response
You've already chosen the best response.
1
@Callisto
amistre64
Best Response
You've already chosen the best response.
0
im not sure since we havent gone over this in my physics class yet, but i would say that 20% efficiency means that 20% of the 1000 cals are used; giving us 200 cals in the answer at least
SheldonEinstein
Best Response
You've already chosen the best response.
3
May I help?
amistre64
Best Response
You've already chosen the best response.
0
please do :)
mayankdevnani
Best Response
You've already chosen the best response.
1
ofcourse @SheldonEinstein
SheldonEinstein
Best Response
You've already chosen the best response.
3
;) OK so first of all what @amistre64 discussed in his previous comment is very imp. to do this quest., so @mayankdevnani do you know what does efficiency mean?
mayankdevnani
Best Response
You've already chosen the best response.
1
ok @amistre64 then
mayankdevnani
Best Response
You've already chosen the best response.
1
yaa
mayankdevnani
Best Response
You've already chosen the best response.
1
efficiency=winout/winin*100
mayankdevnani
Best Response
You've already chosen the best response.
1
right @SheldonEinstein
SheldonEinstein
Best Response
You've already chosen the best response.
3
Yeah or in simpler words it is : \(\large{\frac{\textbf{Output}}{\textbf{Input}}\times 100}\) it is 100%...
mayankdevnani
Best Response
You've already chosen the best response.
1
yaa
SheldonEinstein
Best Response
You've already chosen the best response.
3
So, what we have is output/input * 100% = 20% , correct?
mayankdevnani
Best Response
You've already chosen the best response.
1
correct
SheldonEinstein
Best Response
You've already chosen the best response.
3
Ok so now, let me understand the second line of the quest. , is the output = 1000 calorie ?
mayankdevnani
Best Response
You've already chosen the best response.
1
yaa
mayankdevnani
Best Response
You've already chosen the best response.
1
then
mayankdevnani
Best Response
You've already chosen the best response.
1
@SheldonEinstein then
SheldonEinstein
Best Response
You've already chosen the best response.
3
Oh sorry wait!
mayankdevnani
Best Response
You've already chosen the best response.
1
yaa
SheldonEinstein
Best Response
You've already chosen the best response.
3
I am getting diff. answer so I am checking it, sorry , it will require some patience.
mayankdevnani
Best Response
You've already chosen the best response.
1
ok
SheldonEinstein
Best Response
You've already chosen the best response.
3
Quest. is wrong
mayankdevnani
Best Response
You've already chosen the best response.
1
why?? no it is right
SheldonEinstein
Best Response
You've already chosen the best response.
3
Time is not given.. though if you take 1 minute it is 200 cal.
mayankdevnani
Best Response
You've already chosen the best response.
1
yaa
SheldonEinstein
Best Response
You've already chosen the best response.
3
See , Power = 1000 cal/minute (given)
SheldonEinstein
Best Response
You've already chosen the best response.
3
use this and you will get 200 cal. as answer.
mayankdevnani
Best Response
You've already chosen the best response.
1
so what's the work done?
SheldonEinstein
Best Response
You've already chosen the best response.
3
W = P * time
if T = 1 second , W = P ...
that's it , find P(output) .. (using efficiency = Ouput/Input *100%) in Cal. per minute , that will be your answer
SheldonEinstein
Best Response
You've already chosen the best response.
3
200 cal.... = WORK DONE
mayankdevnani
Best Response
You've already chosen the best response.
1
no
mayankdevnani
Best Response
You've already chosen the best response.
1
but the work done is in joule
mayankdevnani
Best Response
You've already chosen the best response.
1
@ParthKohli @Preetha
mayankdevnani
Best Response
You've already chosen the best response.
1
@SheldonEinstein
mayankdevnani
Best Response
You've already chosen the best response.
1
@myininaya
SheldonEinstein
Best Response
You've already chosen the best response.
3
Is my answer correct, i.e. 200 cal, 873 J ?
mayankdevnani
Best Response
You've already chosen the best response.
1
yaa
SheldonEinstein
Best Response
You've already chosen the best response.
3
So where is the problem? ?? ? ?
mayankdevnani
Best Response
You've already chosen the best response.
1
873 J how??
mayankdevnani
Best Response
You've already chosen the best response.
1
@amriju
mayankdevnani
Best Response
You've already chosen the best response.
1
@SheldonEinstein how you got it 873J
SheldonEinstein
Best Response
You've already chosen the best response.
3
I got 200 Cal, and it is in options, soo....
mayankdevnani
Best Response
You've already chosen the best response.
1
but it's wrong
mayankdevnani
Best Response
You've already chosen the best response.
1
i need solution
mayankdevnani
Best Response
You've already chosen the best response.
1
can you help me @amriju
SheldonEinstein
Best Response
You've already chosen the best response.
3
200 cal * 4.184 = 836 J (approx. ) not equal to 873 Joule , hence I think the options are wrong..
mayankdevnani
Best Response
You've already chosen the best response.
1
no it was not wrong
amriju
Best Response
You've already chosen the best response.
0
work done is 20 percnt of the energy given...thats efficiency....so per minute is 20percnt of 1000 cal...thats 200 cal...convert to joules
mayankdevnani
Best Response
You've already chosen the best response.
1
so 1cal.=? j @amriju
amriju
Best Response
You've already chosen the best response.
0
4.2...approx..the correct is 4.187...
mayankdevnani
Best Response
You've already chosen the best response.
1
is it 4.37
amriju
Best Response
You've already chosen the best response.
0
nope
mayankdevnani
Best Response
You've already chosen the best response.
1
why??
amriju
Best Response
You've already chosen the best response.
0
thats how it is defined...both are units...and 1 cal is defined as 4.187 joules...
SheldonEinstein
Best Response
You've already chosen the best response.
3
That is what I was saying @amriju
mayankdevnani
Best Response
You've already chosen the best response.
1
in my solution book...the answer is as follows-
\[\frac{20}{100}=\frac{W}{1000}=200 calorie\]
OR
\[200\times4.37=873J\]
mayankdevnani
Best Response
You've already chosen the best response.
1
is that right?? @amriju and @SheldonEinstein
SheldonEinstein
Best Response
You've already chosen the best response.
3
That is wrong, 1 Cal. = 4.187 Joule NOT 4.37 joule...
mayankdevnani
Best Response
You've already chosen the best response.
1
ok... thnx... @SheldonEinstein and @amriju
amriju
Best Response
You've already chosen the best response.
0
u may jst check on wikipedia...and its seems that none of the options are correct...the closest being 200, 837
amistre64
Best Response
You've already chosen the best response.
0
if your options are truely: 200,873
then its most likely a typo and prolly meant to be read as 200,837