A copper sphere of diameter 18 cm is drawn into a wire of diameter 4 mm. Find the length of the wire.(in meters )
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volume of sphere = volume of wire
Volume of sphere= 4/3 πR^3, Volume of cylinder= πr^2 h, When a sphere is turned into a wire then the wire act like a cylinder. So here we have radius of sphere,R = 18/2=9 cm Radius of wire, r = 4/2=2 mm= 0.2 cm So , volume of sphere= Volume of cylinder Or, 4/3 πR^3 = πr^2 h Or, 4/3 π〖(9)〗^3 = π〖(0.2)〗^2 h Or, h= 243 m
vol. of sphere=vol. of cylinder; 4/3(pi)r^3=pi(R^2)h ; where, r=radius of the sphere,r=radius of sphere & h=height of the cylinder i.e,length of the wire 4/3(3.14)(0.09^3)=(3.14)(0.002^2)h so,h=4/3(3.14)(0.09^3)/(3.14)(0.002^2 ) hence,h=243m(sol.)
We know the volume of a sphere is 4/3x22/7xr^3. Therefore the volume of the given sphere is 21384/7. Now the wire is in the form of a cylinder so volume of a cylinder is 22/7xr^2xh. So by the problem 22/7xr^2xh=21384/7. So by solving the equation we get h=243 meters.
The volume of a sphere is 3 4 \ * pi * r * r* r ) = 3 4 * pi * 0.09 * 0.09 * 0.09 = 0.000972 pi.
The volume of a cylinder is pi * r * r * h = pi * 0.002 * 0.002 * h = 0.000004h * pi.
Since they are from the same materials, they have the same volume.
Thus, 0.000972 pi = 0.000004h * pi. h = 0 . 0 0 0 0 0 4 0 . 0 0 0 9 7 2 = 243m
The formula for the volume of a sphere is 3 4 π r 3 .The problem gives us the diameter of the sphere.The radius of the sphere is equal to half of the diameter so r = 2 1 8 c m = 9 c m .So the volume of the copper sphere is 3 4 × π × 9 c m × 9 c m × 9 c m = 9 7 2 π c m 3 .
The formula for the volume of a cylinder is h π r 2 where h is the height( in this case the length) of the cylinder and r is the radius of the base.The radius of the copper wire is 2 0 . 4 c m = 0 . 2 c m .So the volume of the wire is h π 0 . 0 4 c m 2 .
Because the entire copper sphere is drawn into the wire,the volume of the sphere must be equal to the volume of the wire.So we get
9 7 2 π c m 3 = h π 0 . 0 4 c m 2
Now we divide both sides by π .We get
9 7 2 c m 3 = 0 . 0 4 h c m 2
Then we divide both sides by 0 . 0 4 c m 2 and we get
2 4 3 0 0 c m = h
So h = 2 4 3 0 0 c m .But the question is asking for the length in meters,so we convert 2 4 3 0 0 c m to meters and we get 1 0 0 c m 2 4 3 0 0 c m = 2 4 3 m .So the answer is 2 4 3 m .
VOLUME OF SPHERE=4/3 X 22/7 X R^3
VOLUME OF WIRE(VOLUME OF CYLINDER)=22/7 X r^2 X H
VOLUME OF SPHERE=VOLUME OF CYLINDER
4/3 X 22/7 X R^3=22/7 X r^2 X H
4/3 X 9 X 9 X 9=2/10 X 2/10 X H
24300 CM=H
243 METERS=H
volume will remain constant & hence volume of sphere = volume of wire(cylinder)
Even surface area will remain constant right??
Volume of sphere = 3 4 π r 3
Volume of cylinder = π r 2 h
3 4 π r 3 = π r 2 h
3 4 π ( 0 . 0 9 ) 3 = π ( 0 . 0 0 2 ) 2 h
Divide the π of that equation
3 4 × 0 . 0 0 0 7 2 9 = 0 . 0 0 0 0 0 4 × h
h = 0 . 0 0 0 0 0 4 3 4 × 0 . 0 0 0 7 2 9
h = 0 . 0 0 0 0 0 4 0 . 0 0 0 9 7 2
h = 2 4 3
So the length is 2 4 3
(4xπx0.09^3)/3=πx0.002^2xh
h=243m
V_sphere = V_wire ---> 4/3.phi.(180/2)^3 = phi.(4/2)^2.h ---> 4/3 . 729000/3 = 4 .h ----> 729000/3 [mm]= h ----> h = 243000/1000 [m] = 243 m. Answer : 243 . HAPPY CHRISTMAS DAY
The volumes of the sphere and the wire have to be equal, since the same material is used for both. The volume of a sphere of radius r is 3 4 π r 3 while the volume of a wire (which is in fact a very thin cylinder) is given by π r 2 l , where r is the radius of the wire and l is its length.
Converting all given lengths to centimeters (for convenience):
V s p h e r e = 3 4 π ( 1 2 1 8 ) 3 = 9 7 2 π
V c y l i n d e r = π ( 2 0 . 4 ) 2 l = 0 . 0 4 π l
⇒ 0 . 0 4 π l = 9 7 2 π
⇒ l = 2 4 3 0 0 c m = 2 4 3 m
Volume of Sphere= 4/3 (pi)(r^3)=4/3(pi)(0.09)^3
Length of Wire=(4/3(pi)(0.09)^3) / ((pi)(0.002)^2)=243m
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We know that when any solid is melted or drawn and given a new shape, the volume remains the same as before.
Let l be the length of the wire.
So, volume of the sphere in metres = 3 4 π r 3 = 3 4 π ( 2 × 1 0 0 1 8 ) 3
Now, after being drawn into wire, its volume in metres = π r 2 l = π ( 2 × 1 0 0 0 4 ) 2 l
Now, we have 3 4 π ( 2 × 1 0 0 1 8 ) 3 = π ( 2 × 1 0 0 0 4 ) 2 l
⟹ 3 4 π × 2 0 0 1 8 × 2 0 0 1 8 × 2 0 0 1 8 = π × 2 0 0 0 4 × 2 0 0 0 4 l
On evaluating, we finally get, l = 9 × 3 × 9 = 2 4 3
So, we get the length of the wire = l = 2 4 3