Hello, I really need help with these problems. I just can't figure out how you know where to plug in the numbers in the formulas y=kx, y=k/x, and y=kxz. I've asked for help from the professor and number of times and the way she explains it to me I just don't understand. She doesn't do a lot of explaining actually, just asking questions of the next step and me guessing until I'm right and she doesn't explain to me why it's right or how that is comparitive to another problem.
8.9 Variation 707 .rgan Pipes. The frequency of vibration of air in an organ @ructural Engineering. The deection of a beam is inversely pipe is inversely proportional to the length of the pipe. If a pipe proportional to its width and the cube of its depth. If the 2 feet long vibrates 256 times per second, how many times per deection of a 4inch-Wide by 4-inch-deep beam is second will a 6foot pipe vibrate? 1.1 inches, nd the deection of a 2-inch-wide by 8-inch-deep beam positioned as in gure (a) below, i, ,. ' ~ , ' Y'lidlt'h Force Width F 1 . ' ' ' - . . l || OI'CC Depth 'l' T 41. Gas Pressure. Under constant temperature, the volume occupied by a gas varies inversely to the pressure applied. If the gas occupies a volume of 20 cubic inches under a pressure of 6 pounds per square inch, nd the volume when the gas is (a) (b) . subjected to a pressure of 10 pounds per square inch. ;:\\ @eal Estate. The following table shows the listing price for @tructural Engineering. Find the deection 0f the beam in three homes in the same general locality. Write the variation Exercise 47 when the beam is positioned as in gure (13) above. model (direct or inverse) that describes the relationship between the listing price and the number of square feet of a 49. Electronics. The resistance of a wire is directly proportional to house in this area. the length of the wire and inversely proportional to the square of the diameter of the wire. If the resistance is l 1.2 ohms in a Number of square feet 80-foot-long wire with diameter 0.01 inch, what is the 1 720 resistance in a l60-foot'long wire with diameter 0.04 inch? 1,205 wusiness Models. A businessman who sells widgets has 1,080 ound that the revenue from their sale varies directly as the advertising budget and inversely as the price. When $105,000 was spent on advertising and the widgets were priced 43. ,Trucking Costs. The costs of a trucking company vary jointly . at $19.95, the revenue from their sale was $200,000. What as the number of trucks in service and the number of hours they are used. When 4 trucks are used for 6 hours each, the revenue would he expect if the widgets were priced at $1750 costs are $1,800. Find the costs of using 10 trucks, each for 12 each and $700'000 was spent on advertismg? 51 Tension in a String. When playing with a Ski It to , a child hours. _ . . 'p .y @Oil Storage. The number of gallons of oil that can be stored in swmgs a weighted ball on the end ofa string m a circular a cylindrical tank varies jointly as the height of the tank and the motion around one leg whilejumping over the revolving string square of the radius of its base. The constant of proportionality With the other leg. See the Illustration. The tension T in the is 235. Find the number of gallons that can be stored in the string is.direct1y proportional to the square of the speed s of the ball and inversely proportional to the radius r of the circle. If the tension in the string is 6 pounds when the speed of the ball is 6 feet per second and the radius is 3 feet, nd the tension when the speed is 8 feet per second and the radius is 2.5 feet. cylindrical tank shown. Hlet>l 45. ectronics. The voltage (in volts) measured across a resistor is directly proportional to the current (in amperes) owing through the resistor. The constant of variation is the resistance (in ohms). If 6 volts is measured across a resistor carrying a current of 2 amperes, nd the resistance. 46. Electronics. The power (in watts) lost in a resistor (in the form of heat) varies directly as the square of the current (in amperes) passing through it. The constant of proportionality is 52. Gas Pressure. the resistance (in ohms). What power is lost in a 5-0hm resistor carrying a 3-ampere current? The pressure of a certain amount of gas is directly proportional to the temperature (measured on the Kelvin scale) and inversely proportional to the volume. A sample of gas at a pressure of 1 atmosphere occupies a volume of 1 cubic meter at a temperature of 273 Kelvin. When heated, the gas expands to twice its volume, but the pressure remains constant. To what temperature is it heated
