How much work W

Question

A force of 14 lb is required to hold a spring stretched 8 in. beyond its natural length. How much work W is done in stretching it from its natural length to 13 in. beyond its natural length?

Answer 1

We can use the formula or work.

 

W = Fd

 

where:

W = work

F = force

d = elongation of spring

 

 

Since the elongation changes in the spring, so does the work done on the spring.  So we must find the difference of work according to the elongation.

 

W_{13 in} - W_{8 in} = (14 lb)(13 in) - (14 lb)(8 in)

                   = 14 lb (13 in - 8 in)

                   = (14 lb) (5 in)

                   = 70 lb in

 

The work done is 70 lb in.