Plastic drum of cylindrical shape is made by melting spherical solid plastic balls of radius 1cm.find the number of balls required to make a drum of thickness 2cm,height 90cm and outer radius 30cm(drum has no lid)
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1350 balls required to make a drum
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external radius , R= 30 cm
thickness = 2 cm
internal radius, r= 30-2= 28 cm
external height = H= 90 cm
internal height =h= 90-2=88 cm
volume of plastic drum = pi R^2H - pi r^2h
pi( 30^2 *90- 28^2*88)
pi ( 81000-68992)
12008 pi cm^3
let the number of balls melted be x
volume of plastic balls
x*4/3 pi (radius^2)
x*4/3 pi * 1*1
4 pi x /3
volume of plastic balls = volume of balls in the drum
4 pi x/ 3= 12008 pi
x =9006
thickness = 2 cm
internal radius, r= 30-2= 28 cm
external height = H= 90 cm
internal height =h= 90-2=88 cm
volume of plastic drum = pi R^2H - pi r^2h
pi( 30^2 *90- 28^2*88)
pi ( 81000-68992)
12008 pi cm^3
let the number of balls melted be x
volume of plastic balls
x*4/3 pi (radius^2)
x*4/3 pi * 1*1
4 pi x /3
volume of plastic balls = volume of balls in the drum
4 pi x/ 3= 12008 pi
x =9006
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