Physics, 10.05.2021 20:10 adi47

One system collects waste products and turns them into urine. A. Respiratory System B. Muscular System C. Nervous System

D. Circulatory System E. Digestive System F. Excretory System

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Answer from: Quest

report!

explanation:

physics means: "the branch of science concerned with the nature and properties of matter and energy. the subject matter of physics, distinguished from that of chemistry and biology, includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms."

Answer from: Quest

Distance covered = speed x timethe distance traveled going against the stream = distance traveled with the stream.therefore it is the speed and the time that are the variables.as he travels the same distance both ways, speed x time is the same for each way.going upstream his speed is 4 kph; going downstream his speed is 6 kph.therefore we have two simultaneous equations: time upstream x 4 = time downstream x 6time upstream + time downstream = 60 minutestherefore we have the equation: time upstream = 6/10 hour, time downstream therefore = 4/10 hour.distance traveled at 4km/hr in 6/10 hour = 24/10 = 2.4km.check: distance traveled at 6km/hr in 4/10 hour = 24/10 = 2.4km.

Answer from: Quest

195, i took the test already.

Answer from: Quest

This is actually a calculus question. so, basically, this is a related rates question where you are given 1 quantity and you have to find the other. we'll define some variables first.x = 9 ftdx/dt = 7 ft/secl = 15 ftsince you want to find the area, you have to find a formula for it. which is: $a = \frac{1}{2}x*h$ we know the base (x), but we don't know the height (h). we can figure it out by solving for it. we have to form an equation which we can figure out height from given the information we have. this equation is: $x^2+h^2=l^2$ plug in known values: $9^2+h^2=15^2$ solve for h: $h^2 = 15^2-9^2$ $h^2=144$ $h = \sqrt{144}=12$ now, let's solve for the rate at which h is changing. we can do so by differentiating the pythagorean theorem (above). let's do that: $x^2+h^2=15$ $2x \frac{dx}{dt}+2h \frac{dh}{dt}=0$ $\frac{dh}{dt} = \frac{-2x \frac{dx}{dt} }{2h}$ $\frac{dh}{dt} = \frac{-x \frac{dx}{dt} }{h}$ plug in values: $\frac{dh}{dt} = \frac{-9*7}{12} = \frac{-63}{12} = \frac{-21}{4}$ now we have all the given information to do this problem. so, to figure out the rate of change of area, we can differentiate (with respect to time) the earlier equation: $\frac{d}{dt}(a) = \frac{d}{dt} (\frac{1}{2}x*h)$ which is equal to: $\frac{da}{dt}= \frac{1}{2}( \frac{dx}{dt}h+x \frac{dh}{dt})$ plug in known values: $\frac{da}{dt} = \frac{1}{2}(7*12+9* \frac{-21}{4} ) = \frac{1}{2}(84- \frac{189}{4} )$ $\frac{1}{2}( \frac{147}{4}) = \frac{147}{8}$ so, the area of the triangle is changing at approximately 18.375ft²/sechope this all makes sense. if it doesn't, either contact me, or watch khan academy - he explains it real well. special credit to turtaniumx and quietself for letting me know of the error, and fix it!