Answer:
34
Step-by-step explanation:
E = 75% = 0.75, Work Output = Useful Work = 240 J, Work Input = ?
Efficiency, E = Work Output / Work Input
0.75 = 240 / Work Input
Work Input = 240 / 0.75
Work Input = 320
Amount of work supplied = Work Input = 320 J
I hope this explains it.
Answer:
No.
Step-by-step explanation:
y/x has to be the same number no matter what except at point (0 0) which it must also include for it to be a direct variation.
*y=2x+3 is not a direct variation because you can not write it as y/x=k where k is some constant number. If we were y=2x, then yes since y/x=2.
*You could also take two points and see if they are proportional. That is, you can see if y2/x2 gives the same value as y1/x1 where (x1,y1) and (x2,y2) are points on the line y=2x+3. This must work for every pair of points on the linear relation except at x=0 (where you would or should have y=0 if it is directly proportional).
Let's try it out. If x=1, then y=2(1)+3=5.
5/1=5
If x=2, then y=2(2)+3=7
7/2=3.5
As you can see 5 doesn't equal 3.5.
*For it to be a direct variation, it also must contain the point (0,0) and be a diagonal line when graphed. It can also be written in form y=kx where k is a constant number. This fails two of the the things I mentioned. It doesn't contain point (0,0) because y=2(0)+3=3 not 0. It cannot be written in form y=kx because of the plus 3.
If it were y=2x, then the answer would be yes.
