Question

the horsepower produced by a steam engine varies directly as the number of revolution per minute of its operation . if 1200 horse power was produced when a machine was operated at 150 revolutions per minute , find the number of horse power it will produce when it will operate at 170 revolution per minute . ?





The current I in amperes is inversely proportional to resistance R in ohms . if the current is 30 amperes when the resistance is 3 ohms what is the current when the resistance is 5 ohms?

Answer 1

1200 = 150 m
y = 170 m

Answer 2

second one, similar
300 = m/3
y = m/5

Answer 3

you should just solve for m in both cases

Answer 4

and then use that to find y

Answer 5

what the is the formula that used ?

Answer 6

Well, direct variation is \[y = mx\] where m is called the constant of variation.
Inverse variation is \[y = \frac{m}{x}\] and m is also the constant of variation

Answer 7

I used this approach because that is the way the question was phrased, you could also use a proportion, such as\[\frac{1200}{150}=\frac{y}{170}\]

Answer 8

what is different of m and k ?

Answer 9

you could use k if you wanted

Answer 10

they're just variables

Answer 11

ahhhh. ok .

Answer 12

you could also do
\[y = \beta x\]
or


Variables are whatever you want! :)