Thursday, February 17, 2011

Math Textbook Pg 250-253 #2,5,8,10

Jennily's Volume Post # 2,5,8,10

No it doesn't matter.
For example look at these two rectangular prism.

V= area of base x height
V= 50cm x 15cm
V= 750cm

V= area of base x height
V= 75cm x 10cm
V=750cm
You see they are both the same.

LxWxH
4cm x 3cm = 12cm
12cm² x 5cm = 60cm³

LxWxH
5cm x 3cm = 15cm
15cm² x 4 = 60cm³

LxWxH
20cm x 6cm = 120cm
120cm² x 8cm = 960cm

LxWxH
8cm x 6cm = 48cm
48cm² x 20 = 960cm³

So, mainly 1cm cube would look like this:
So if you were to make a base of fifteen cm cube it would look something like this:

The top of this layer should be 15cm² so we would use that as our base.

Since the prism is made up of 5 layers of the 15 cm cubes then i will be using that as my height.
V= area of base x height
V= 15cm² x 5cm
V=75cm³

Even if the wording is different it's basically just asking for the volume.

V= area of base x height
V= 1250cm² x 100cm
V= 125 000cm³

Cylinder Volume and Volume Problems
7.3

A)
V= π x r x r x h
V= (3.14 x 5 x 5) x 23
78.5cm ^2 x 23
V= 1805.5cm^3

B)
V= π x r x r x h
V= (3.14 x 14 x 14) x 12
615.44cm^2 x 12
V= 7385.28cm^3

C)
V= π x r x r x h
V= (3.14 x 0.5 x 0.5) x 1.5
0.785m^2 x 1.5
V= 1.1775m^3

7.4

A) Yes, He has enough small prism. If he uses 4 for the base and 4 for the height he will have enough.
B)
b x h / 2 x h
5.6 x 6.8 / 2 = 19.04m ^2
19.04m^2 x 1.18 = 22.4672m^ 3

1 comment:

1. Good job Jennily. Your post was neat and I liked how you said that question 10 was just asking for the volume. Next time try adding a Flisti.