Question

Question - How much leads of specific gravity 11 must be added to a piece of cork of specific gravity 0.2 weighing 10g so that it just floats on water?
a) 2.2 g b) 4.4 g c) 44 g d) 440g

Answer 1

Answer:

c) 44 g

Explanation:

we want the specific gravity to end up being one, exactly that of waters.

since th ecork as a sp. gravity of .2, its 10 grams will take up 50 (10/.2) times the volume as 10 grams of water. we need to get the mass/volume ratio equal to waters. Since the lead has a sp grav of 11, every equal volume of water it takes up will be 11 times as heavy.

so the total mass we will have is 10 + 11*v (where v is volume of lead)

total volume will be 50 + v

(10 + 11v) / (50+v) = 1

10 + 11v = 50 + v

10v = 40

v =4

so we need 4 extra water volumes of lead which is equal to 44 extra masses. The units should still be in g.

Check:

(10g + 44g) / (50 wu + 4 wu)

= 54 grams / 54 water units

= 1 gram / water volume unit

which is what it should be. Note that you could actally use the real density of water to get the volume in real units instead of the ones I just made up.

answer is 44 g

Answer 2

Hi!!!

Answer:Your answer will be ;- 44 gms

Explanation:We want the specific gravity to end up being one, exactly that of waters.

Cork specific gravity = 0.2

Specific gravity = density of object ÷ density of water.(Density of water = 1 )

So,

density of Cork will be = 0.2 × 1 = 0.2

And density of lead will be = 11 × 1 = 11

Density = mass ÷ volume.

So, volume of Cork = 10g ÷ 0.2 = 50

"we need to get the mass/volume ratio equal to waters. "

Mass of lead will be = 11 × v

( v = volume of lead, assumed)

So,

the total mass we will have is = (10 + 11v) gm

And total vol. will be = (50 + v)L

---->(10 + 11v) / (50+v) = 1

---->10 + 11v = 50 + v

---->10v = 40

---->v =4 L

So,

we need 4 extra water volumes of lead which is equal to 44gm extra masses.

Mass of lead = 11 × 4 = 44gm.

Hope you get the answer.

Pleased to help you.