At some point, however, you will be able to extend elastic objects to a point where they will not restore their shape. This point is known as the elastic limit.
17.5
Fig. 17.5.4 A spring before and after being extended beyond its elastic limit
What is the relationship?
Extension of spring (cm)
0 2 4 6 8
10 12 13 14
Force applied by weights in pan (N)
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
The set of data in this table was recorded in an investigation where students extended a spring by adding weights to a pan. Using the data:
1. Plot a suitable graph. Determine from the graph when the elastic limit of the spring was reached.
2. Up to the point where the elastic limit was reached, could you suggest what the relationship was between the extension of the spring and the force applied by the weights in the pan?
F Crash!
Using the particle theory (see Chemical World 9.1) and your understanding of compressing forces, work with your lab partner to design a poster explaining why a tackle bag is used in sports training rather than allowing people to run into wooden tables.
z What function do you want the bag to perform? z What states of matter exist within the bag?
Golf balls are
designed to compress when struck with the golf club. They apply a force to restore to their normal shape in flight, allowing them to reach speeds upwards of 280 km/h.
