Hooke’s law states that when a spring is stretched, it pulls back with a force proportional to the amount of the stretch. The constant of proportionality is a characteristic of the spring known as the spring constant. Thus a spring with spring constant k exerts a force f(x2)= kx when it is stretched a distance x. A certain spring has spring constant k =20 lb/ft. Find the work done when the spring is pulled so that the amount by which it is stretched increases from x =0 to x = 2 ft.
Hooke’s law states that when a spring is stretched, it pulls back with a force proportional to the amount of the stretch. The constant of proportionality is a characteristic of the spring known as the spring constant. Thus a spring with spring constant k exerts a force f(x2)= kx when it is stretched a distance x.
A certain spring has spring constant k =20 lb/ft. Find the work done when the spring is pulled so that the amount by which it is stretched increases from x =0 to x = 2 ft.
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We need to find the amount of work done in pulling the spring from x=0 to x=2 if the spring with spring constant k exerts a force when it is stretched a distance x .
The work done in moving an object from a to b is defined as the limit of this quantity as.
and
To determine the work done, we first need to evaluate the value of and .
We have.
On substituting , we get
On substituting a=0 and in , we get
On substituting in we get
On substituting the value of in, we get
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