Homework Help

geometryplease help wih these questions i am totally confused.. thank you 1. find the...

user profile pic

gutierrezsally | Student, Undergraduate | (Level 2) Honors

Posted January 21, 2012 at 8:51 AM via web

dislike -1 like
geometry

please help wih these questions i am totally confused.. thank you

1. find the volume of a sphere that has a radius of 1.2m.

2. the height of a cylinder is 7.2m the radius of the base is 4m. find the voume of the cylinder. gie the exact measure pls.

3. the height of a cone is 15cm. the diameter of the cone is 10cm. find the voume of the cone.

4. a rectangukar tank is 9m long 3m wide and 1.5m deep. find he volume of thw water in the tank when the tank is full.

 

6 Answers | Add Yours

user profile pic

pohnpei397 | College Teacher | (Level 3) Distinguished Educator

Posted January 21, 2012 at 10:27 AM (Answer #3)

dislike 0 like

With #4, what you have to do is multiply all three together.  Multiply length and width and that gets you area, right?  In this case, 27 m^2.  Then multiply that by the depth to get volume.  27*1.5 = 40.5.  So the volume of your tank should be 40.5 m^3.  Just remember, for the volume of a rectangular thing, it's width x length x depth.

user profile pic

literaturenerd | High School Teacher | (Level 2) Educator Emeritus

Posted January 21, 2012 at 10:36 PM (Answer #5)

dislike 0 like

The formula to find the volume of a sphere is: volume= 4/3 (3.14) (r cubed).

The formula to find the volume of a cylinder is: volume= 3.14(r squared)(h).

The formula to find the volume of a cone is: volume= 1/3 (3.14)(r squared)(h).

The formula to find the volume of a rectangle box is: volume=(l)(w)(h).

r= radius

h= height

w= width

user profile pic

gutierrezsally | Student, Undergraduate | (Level 2) Honors

Posted January 22, 2012 at 10:14 AM (Answer #7)

dislike 0 like

the reason i posted this as a discusion is to get an understanding of what i am doing question and answers is not what am looking for.. i am looking for a way to do the problems because i am stuck.. so thank you number 5 for helping me to figure out what i am doing..

user profile pic

boblawrence | (Level 1) Associate Educator

Posted January 24, 2012 at 7:37 AM (Answer #8)

dislike 0 like

The formulae for volume of sphere, cylinder and cone are not intuitively obvious, lnor easily derrived.  Therefore, when one studies geometry, she looks up the formulae, then memorizes them.  Once you have the formulae (as given in answer 5), it is a simple matter of plugging in the numbers and calculating.

 

 

user profile pic

sciencesolve | Teacher | (Level 3) Educator Emeritus

Posted January 27, 2012 at 1:16 AM (Answer #9)

dislike 0 like

1) You need to write down the formula of volume of sphere such that:

V = (4/3)*pi*r^3

Substituting 1.2 m for radius in formula of volume yields:

V = (4/3)*pi*(1.2)^3 => V = 2.304 pi m^3

2) You need to write down the formula of volume of cylinder such that:

V = Area of base*height = pi*r^2*h

Area of base = Area of circle = pi*r^2

h denotes the height of cylinder

Substituting 4 m for radius and 7.2 m for height in formula of volume yields:

V = pi*16*7.2 = 43.2 m^3

3) You need to remember the formula of volume of cone such that the volume of cone is one third of volume of cylinder, hence:

V = (pi*r^2*h)/3

Since the diameter of circle is of 10 cm => radius is one half of diameter such that r = 10/2 = 5 cm.

V = (pi*25*15)/3 = 125 pi cm^3

4) The volume of tank is V = area of rectangular base multiplied by height of tank such that:

V = 9*3*1.5 = 10.5 m^3

user profile pic

Jyotsana | Student, Grade 10 | (Level 1) Valedictorian

Posted March 8, 2014 at 11:25 PM (Answer #10)

dislike 0 like

1. Volume of Sphere= 4/3*3.14*1.2^2= 6.03m

2. Volume of Cylinder= 3.14*4^2*7.2= 361.73m

3. diameter=10  r=10/2=5

Volume of Cone=1/3*3.14*5^2*15=392.5cm

4. Volume of Rectangular=9*3*1.5= 40.5m

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes