scale drawings and scale models
DESCRIPTION
Scale Drawings and Scale Models. Vocabulary. scale drawing : proportional two-dimensional drawing of an object (smaller or larger) scale model: proportional three-dimensional model of an object (smaller or larger) - PowerPoint PPT PresentationTRANSCRIPT
Scale Drawings and
Scale Models
Vocabulary
scale drawing: proportional two-dimensional drawing of an object (smaller or larger)
scale model: proportional three-dimensional model of an object (smaller or larger)
scale factor: a ratio of the model/drawing’s dimensions to the actual object’s dimensions in simplest form
scale: ratio between two sets of measurements
Examples of Scale Drawings
blueprints maps
Examples of Scale Models
toy carmodel of a house
toy airplane
Finding Scale Factor
model’s dimensionsactual object’s dimensions
Caution!!!
A scale factor is ALWAYS the ratio of the model’s
dimensions to the actual object’s dimensions.
Caution!!
It’s alright to have a scale factor greater than 1. If the scale factor is greater
than 1, this means that the new figure is bigger than the original (think about cells). If the scale factor is less than 1, then the new figure is smaller than the original (think about model airplanes).
Finding a Scale Factor
Airplane Model
Length (in.)
1,800 20
Height (in.)
756 8.4
You can use the lengths or heights to find the scale factor.
MODEL LENGTH
AIRPLANE LENGTH
20
1,800
÷ 20
÷ 20
THEN SIMPLIFY!
20
1,800
=1
90
SCALE FACTOR!
Finding a Scale Factor
Airplane Model
Length (in.)
1,800 20
Height (in.)
756 8.4
You can use the lengths or heights to find the scale factor.
MODEL HEIGHT
AIRPLANE HEIGHT
8.4
756
÷ 8.4
÷ 8.4
THEN SIMPLIFY!
8.4
756
=1
90
SCALE FACTOR!
Finding a Scale Factor
Great Dane
Model
Height (in.)
35 10
MODEL HEIGHT
GREAT DANE HEIGHT
10
35
÷ 5
÷ 5
THEN SIMPLIFY!
10
35
=2
7
SCALE FACTOR!
Using Scale
On a road map with a scale of 1 cm: 120 mi., the distance between two cities measures 3.5 cm. What is the actual distance between these two cities?
MODEL
ACTUAL
1 cm
120 mi =
3.5 cm
x mi
420 ÷ 1 = 420
The actual distance between these two cities is 420 miles.
Using Scale
Jeffery is making a model of a car. He uses the scale 1 in:12 in. If the length of the actual car is 132 in., what is the length of his model car?
MODEL
ACTUAL
1 in
12 in =
x in
132 in
132 ÷12 = 11
The length of his model car is 11 in.
Using Scale FactorKelly enlarged her favorite photograph into a poster. The poster is 22 inches by 38 inches. The scale factor is 6/1. Find the size of the original photograph. Round to the nearest tenth.
22 inches
38 inchesx inches
x inches
Using Scale FactorKelly enlarged her favorite photograph into a poster. The poster is 22 inches by 38 inches. The scale factor is 6/1. Find the size of the original photograph. Round to the nearest tenth.
MODEL
ACTUAL
6 in
1 in =
38 ÷ 6 = 6.3
Let’s find length first!
38 in
x in
Using Scale FactorKelly enlarged her favorite photograph into a poster. The poster is 22 inches by 38 inches. The scale factor is 6/1. Find the size of the original photograph. Round to the nearest tenth.
22 inches
38 inches6.3 inches
x inches
Using Scale FactorKelly enlarged her favorite photograph into a poster. The poster is 22 inches by 38 inches. The scale factor is 6/1. Find the size of the original photograph. Round to the nearest tenth.
MODEL
ACTUAL
6 in
1 in =
22 ÷ 6 = 3.6
Now let’s find the width!
22 in
x in
Using Scale FactorKelly enlarged her favorite photograph into a poster. The poster is 22 inches by 38 inches. The scale factor is 6/1. Find the size of the original photograph. Round to the nearest tenth.
22 inches
38 inches6.3 inches
3.6 inches
Now we know...
The original size of the photograph is 3.6 inches by 6.3 inches.
In this case, the scale factor was larger than one. This means, that
the model is larger than the original.
Try This:
On a scale drawing of a horse, the scale is 1 mm: 10 mm. If the real horse is 1,500 mm tall, how tall is the horse on the scale drawing?