Question

You wish to check the quality of timber with the help of sound. Which of the following way should you use for such a scenario?
1. Timber struck by hammer
2. Two timber pieces struck together
3. Timber tapped by steel square
4. Timber knocked by chisel

Answer 1

Correct Answer - Option 2 : Two timber pieces struck together

Concept:

Characteristics of Good Timber:

A timber is said to be good based on the following characteristics :

Characteristics of Timber	Details
Durability	Durability is the first priority for any kind of engineering material. A good timber should be durable enough to resist the actions of chemical agents, biological agents, physical agencies, etc.
Strength	Strength is the resistance against failure. A good timber should not fail easily and it should be strong enough to take loads acting on it. The strength of timber varies depending on the direction (transverse or direct) in which it is loaded.
Permeability	The permeability of timber should be less. A good timber should not absorb more than 8 to 12% of water by its weight when placed in water.
Hardness	Hardness is the resistance against penetration. Good timber should be hard and workable. The hardness of timber depends upon its density and heartwood properties.
Toughness	Toughness is the resistance against sudden shocks and vibrations. A good timber should be tough enough to resist sudden impact loads and vibrations. The toughness of timber is improved by the good interlocking of grains in its structure.
Elasticity	A good timber should be elastic. Elasticity is the property of regaining its original shape after deformation causing loads to be removed.
Workability	The workability of timber is the ease with which it can cut into the required shape. A good timber is easily workable. It should not damage or block the teeth of the saw during cutting.
Structure	A timber with a uniform structure is said to be good timber. The fibers of timber should be straight and firm. The annual rings of timber should be closely located indicating the fact that the tree is mature enough to use it for making timber products.
Colour	The strength of timber can be estimated by looking at its color. Light color designates low strength timber while dark color indicates high strength timber.
Shape	The shape of timber should not be disturbed while cutting and seasoning. A bad timber may bow or warp or split during conversion.
Sound	The velocity of sound in timber (hardwood) is approximately 12 times more than that in the air. A good timber should produce a clear ringing sound when struck by each other. A dull heavy sound designates decayed timber. This is the reason why many musical instruments are made of wood.