To verify Hook’s law for various helical springs and to find their stiffness

To verify Hook’s law for various helical springs and to find their stiffness.

Apparatus

Machine to hold a spring in tension or compression, helical springs of different sizes and weights.

Theory

Stiffness

Stiffness is the resistance of an elastic body to deformation by an applied force along a given degree of freedom (DOF).

Flexibility

Flexibility refers to the absolute range of movement in a joint or series of joints that is attainable in a momentary effort with the help of a partner or a piece of equipment. Flexibility in some joints can be increased to a certain degree by stretching.

Procedure

Work with one spring at a time. Determine the radius of the coil of the spring(r) the diameter of the wire of the coil (d) and (n) the number of coils in the spring. Place the spring in the machine and note the zero reading of the venire. Then apply a load and note the extension or compression of the spring as the case may be.  Do this for W = 2, 4, 6,---------16 lbs. for softer spring and bigger load for harder material spring note the forward and backward readings. Put the readings in the table and draw a graph

Observations and calculations

Spring  Number	Load (lbs)	Extension or compression X (inches)			Stiffness (lbs/inch)	Modulus of Rigidity
		Forward	Backward	Mean
I  Extension r= d= n=
II Compression r= d= n=