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Student Activity - Balancing Act

INTRODUCTION

Metals and other materials are used to make a bike. Several different factors need to be considered when choosing what materials are best for various parts of a bike. One material might be great because it’s lightweight, but dangerous because it too easily snaps when put under any strain. Another material might be very strong but too heavy. Like a cyclist on their bike, it’s a real balancing act!


Australian Team Pursuit-Atlanta Olympic Games 1996 Allsport

INVESTIGATION

This activity looks at the different features of several materials and makes some conclusions about their relative usefulness in constructing a bike. The features are -

WHAT YOU NEED

Samples of wood, steel (eg. nail), aluminium(eg, soft drink can), carbon fibre (eg. graphite tennis racquet) and nylon.

MATERIAL

DENSITY (g/cm)

RELATIVE

STRENGTH

RELATIVE STIFFNESS

Wood

0.5

1

20

Nylon

1.1

0.8

1.5

Carbon-fibre

1.6

18

100

Aluminium

2.7

2

35

Steel

7.8

10

105

Source: 'Physics Matter', England, N. 1995.

QUESTIONS

Examine the samples of wood, steel, aluminium, carbon fibre and nylon and study the table above.

  1. What features of nylon make it suitable for racing bike seats and clothing?

  2. _____________________________________________

  3. Look at the characteristics of steel, aluminium and wood and think about which you would choose to make a bike frame.
    1. What two advantages does steel have over wood?

    2. (i)_____________________ (ii) _____________________

    3. What two advantages does steel have over aluminium?

    4. (i)____________________ (ii)_______________________

    5. Why is aluminium sometimes mixed (alloyed) with steel to make bike frames?

    6. _____________________________________________

  5. Some racing bikes have solid wheels made from a carbon-fibre composite. Why?

  6. _____________________________________________