(Engineering) The current / varies as the electromotive force E and inversely as the resistance R. If in a system, a current of 20A flows through a resistance of 20 ohms with an electromotive force of 100V, find the currect that 150V will send throu+gh the system.

(Navigation) The amount of coal used by a steamship travelling at a uniform speed varies jointly as the distance traveled and the square of the speed. If a steamship uses 45 tons of coal travelling 80 mi at 15 knots, how many tons will it use if it travels 120 mi at 20 knots?

Since current varies directly as E, 1.5(100)V will send 1.5(20) = 30A

c = kdv^2
Since 120/80 = 3/2 and 20/15 = 4/3, the new c will be (3/2)(4/3)^2 * 45 = 120 tons

Ok. I got the same answers. Thanks.

Thanks to the both of you for helping.

the current I varies directly as the electromotive force E and inversely as the resistance R. If a current of 30 amperes flows through a system with 16 ohms resistance and electromotive force a 120 volts,find the current when the current when the system with 20 ohms resistance and electromotive force of 200 volt.the current I varies directly as the electromotive force E and inversely as the resistance R. If a current of 30 amperes flows through a system with 16 ohms resistance and electromotive force a 120 volts,find the current when the current when the system with 20 ohms resistance and electromotive force of 200 volt.

(Engineering) To solve the first question, we can use Ohm's Law:

Ohm's Law states that the current (I) in a circuit is equal to the electromotive force (E) divided by the resistance (R). Mathematically, it can be expressed as:

I = E/R

Given that the current (I) is 20A, the resistance (R) is 20 ohms, and the electromotive force (E) is 100V, we can substitute these values into the formula and solve for the current (I) when the electromotive force is 150V.

20 = 100/20

To find the current (I) with a different electromotive force (E), we can rearrange the equation and solve for I:

I = E/R

I = 150/20

I = 7.5A

Therefore, the current that 150V will send through the system is 7.5A.

(Navigation) To solve the second question, we are given that the amount of coal used by a steamship varies jointly as the distance traveled and the square of the speed. Mathematically, it can be expressed as:

Amount of coal used = k * distance * speed^2

where k is a constant.

We can use the given information to find the value of k. Given that the steamship uses 45 tons of coal when traveling 80 miles at 15 knots, we can substitute these values into the equation:

45 = k * 80 * 15^2

Simplifying the equation:

45 = k * 80 * 225

To find the value of k, we divide both sides of the equation by (80 * 225):

k = 45 / (80 * 225)

Now, we can use the value of k to solve for the amount of coal used when the steamship travels 120 miles at 20 knots:

Amount of coal used = k * distance * speed^2

Amount of coal used = (45 / (80 * 225)) * 120 * 20^2

Simplifying the equation:

Amount of coal used = (45 / (80 * 225)) * 120 * 400

Therefore, the steamship will use (45 / (80 * 225)) * 120 * 400 tons of coal when it travels 120 miles at 20 knots.