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23 Nov 2019

A block of wood floats on water. The density of the
wood is 0.613 g/cm3. Its mass is 243 g. Find the minimum mass (g)of lead we
must attach to the block so that it will sink, along with the lead.The density of lead is
11.3 g/cm3. Caution: you must take into account the buoyant forceon the lead, as well
as on the wood.

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Jarrod Robel
Jarrod RobelLv2
14 May 2019

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Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

Hydrometer Problem: 2Parts
A) Suppose you made your own hydrometer. If its massis11.5 g, what volume will the hydrometer displace in a liquid withadensity of 1.20 g/cm3?
I believe I understand this question. If you dividethemass of the hydrometer, 11.5 g, by the density of the water,1.20g/cm3, you find the volume of the hydrometer to be9.58cm3. Since a solid sinks in a liquid until the massofthe liquid it displaces is equal to its own mass, it woulddisplacethe same volume as itself. So, it would displace9.58cm3.Correct?
B) Suppose the lower part of your hydrometer has avolumeof 7.0 cm3, and the upper part is 5.0cm long andhas across-sectional area of 0.62 cm2. What length oftheupper part of the hydrometer will be submerged?
No idea...
Obtain an overflow can with a short metal tubeextendingoutward a bit below the top of the can. Place the overflowcan on alab jack set at its lowest position. Place a plastic beakernext tothe overflow can so that the plastic beaker will catch anywaterthat overflows. Fill the overflow can until waterstartsoverflowing into the plastic beaker, but don’t let toomuchwater overflow. Once water has stopped overflowing carefullyremovethe plastic beaker making sure not to disturb the overflowcan andweigh the plastic beaker. Record the plastic beaker’sweightand then place it back beside the overflow can. (Recordweights asmass times g where mass is measured in kilograms and g =9.8m/s2.)

Mount a scale on top of a small ring stand. You should findacylindrical slot on the underside of the scale. Pick a metalblockof any material and hang it with a string (about 6 to 8incheslong) from the metal support at the bottom of the scale thatisdirectly connected to the scale’s balance pan (the flathorizontalcircular surface where you usually place objects tomeasure theirmass). With the metal block hanging from the scaledetermine themass of the metal block by balancing the scale.

Carefully move the scale so the metal block is directlyoverthe overflow can and very slowly raise the lab jack so thatthemetal block becomes submerged. Water will overflow into theplasticbeaker. Once water has stopped overflowing re-weigh theplasticbeaker. Also, you will notice that the scale is no longerbalanced.Balance the scale to determine the apparent weight of themetalblock. This “weight” is really equal to the actualweight minusthe buoyant force. From the change in weight of theblock calculatethe buoyant force. Also, from the change in weightof the plasticbeaker calculate the weight of the water displaced.Should theseweights be equal? Compare their values by calculatinga percentdifference.
In part I your instructor may have asked you to use agraduatedcylinder instead of the overflow can. Explain themeasurements thatyou made and how those measurements lead you toconclude thatArchimedes’ Principle is correct.

5) [8 pts] A friend of yours works in a bar as a bartender, and you decide to improve his life by making his job easier. In particular, he has to take empty beer mugs from the bar and put them in the sink (see the diagram below) - and of course, since students come in after exams for a drink, there are a lot of dirty beer mugs to move. You realize that he could send them sliding down the bar and they would land in the sink if they had the right initial speed. You wonder if you can find a single speed (so that he can easily learn to slide them correctly) for different conditions: in particular, if the bar is clean (larger coefficient of kinetic friction between the mug and the bar), or if there is some beer spilt on it (lower coefficient of kinetic friction). The vertical distance from the bar to the surface of the water in the sink is h=0.65m; the horizontal distances from the edge of the bar to the front and back of the sink are dmin=1.2m and dmax=1.8m. The coefficients of kinetic friction are pk=0.25 for a clean bar, and Uk=0.15 for a bar with beer spilt on it. Your friend stands at a point along the bar which is 5.6m from the edge of the bar, and an empty beer mug has a mass of 0.325kg. a) Find the minimum horizontal speed the mug must have when it leaves the bar so that it lands in the sink (at the near edge). b) Using the speed you found in a), calculate the bartender's "launch speed" (ie, the initial sliding speed) for the high-friction case (Uk=0.25). c) Using the speed you found in b) as the initial sliding speed, analyse the low- friction case: find the speed the mug will have when it leaves the bar, and determine whether it lands in the sink (or hits the far wall and shatters, thus making your friend lose his job). d) [for one extra point) Your bartender friend loves your new system, but the next time you visit him you realize he's still walking over to the sink every time he has a shot glass (a glass that's smaller than a beer mug - it's mass is only 0.125 kg) to put there. Does the mass of the glass matter, or can he launch them at the same speed as the mugs without worry (assume the same coefficients of friction as for the beer mug)? dmax beer mug bar sink

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