Name: ____________________________________________
Group: __________
Support activities – Second Year of Secondary Cycle Two
ACTIVITY 58 ANSWER KEY
Date: __________________
ST
STUDENT BOOK: Chapter 13, pages 442–444
RELATED HANDOUT: Concept review 58
Speed changes in motion transmission systems
1. Complete the following sentences, using the words or groups of words in the box below. You
may use some words more than once.
• diameters
• driven components
• driver component
• greater
• number of teeth
• speed change
speed change
a) In motion transmission systems, a ___________________________
occurs when the
driver component
___________________________
does not turn at the same speed as the
driven components
___________________________
. In a worm and worm gear system, the
number of teeth
greater
___________________________
the ___________________________
on the gear, the
greater the decrease in speed. In friction gear systems and belt and pulley systems, a
speed change
diameters
___________________________
occurs when gear ___________________________
are
speed change
different. In gear trains and chain and sprocket systems, a __________________________
number of teeth
occurs when the ___________________________
on the gears varies.
2. What am I?
a) I am the motion transmission system of choice for dramatically reducing the speed of a
rotational motion during transmission.
© ERPI Reproduction and adaptation permitted
solely for classroom use with Observatory.
Worm and worm gear system
b) I am the number of teeth on a gear that turns twice as fast as a gear with eight teeth in a
motion transmission system.
Four teeth
c) I am the diameter of a pulley that turns four times more slowly than a five-centimetre pulley
in a motion transmission system.
Twenty centimetres
Observatory / Guide
11129-B
1
ANSWER KEY
Support activities – Second Year of Secondary Cycle Two
ACTIVITY 58
Speed changes in motion transmission systems
Name: ____________________________________________
Group: __________
Date: __________________
3. For each of the following statements, determine whether there is an increase, decrease or no
change in speed during motion transmission.
a) Motion is transmitted from a friction gear two centimetres in diameter to a friction gear three
centimetres in diameter.
Decrease
b) In a gear train, the motion of a gear with eight teeth is transmitted to a gear with six teeth.
Increase
c) In a gear train, the motion of a gear five centimetres in diameter is transmitted to a gear four
centimetres in diameter.
Increase
4. Look at the three motion transmission systems below.
a) In which of these three systems will there be an increase in speed when motion is
transmitted from component A to component B? Explain your answer.
In system 3, because motion is transmitted from a gear with a larger diameter to one
© ERPI Reproduction and adaptation permitted
solely for classroom use with Observatory.
with a smaller diameter.
b) In which of these three systems will there be a decrease in speed when motion is
transmitted from component A to component B? Explain your answer.
In system 1, because motion is transmitted from a gear with fewer teeth (or a smaller diameter)
to a gear with more teeth (or a larger diameter).
Observatory / Guide
11129-B
2
ANSWER KEY
Support activities – Second Year of Secondary Cycle Two
ACTIVITY 58
Speed changes in motion transmission systems
Name: ____________________________________________
Group: __________
Date: __________________
5. Look at the three motion transmission systems below.
14 teeth
7 teeth
In which of these three systems does the biggest speed change occur? Explain your answer.
The biggest speed change occurs in system 2, because in this system, the difference between the
© ERPI Reproduction and adaptation permitted
solely for classroom use with Observatory.
diameters of the gears is the greatest.
Observatory / Guide
11129-B
3
ANSWER KEY
Support activities – Second Year of Secondary Cycle Two
ACTIVITY 58
Speed changes in motion transmission systems