Forces Acting on Solids

• Forces can alter the object’s size and shape.
• Forces can either:
  • stretch
  • squash
  • bend
  • or twist it.

Examples

• Foam rubber is a great example to investigate how objects deform. When these forces are removed, it springs back to its original shape.
• When a football is kicked, it is compressed for a short while, and springs back to its original shape as it pushes itself off of the player’s foot.
  • This concept applies to a tennis ball when struck by a racket.
• The springiness of the rubber rope from bungee jumpers are important because it breaks their fall when they jump from a height. If the rope became permanently stretched, they would stop suddenly at the bottom of their fall rather than bouncing up and down and gradually coming to a halt.

Materials

• Some materials become permanently deformed when forces act on them.
  • When cars collide, the metal panels of their bodywork are bent.
  • Gold and silver are metals that can be deformed by hammering them.