A spring of force constant `800N//m` has an extension of 5cm. The work done in extending it from 5cm to 15cm is

A spring of force constant 800 N/m has an extension of 5 cm. The work done in extending it from 5 cm to 15 cm is:

A spring of force constant 800 N/m has an extension of 5 cm. The workdone in extending it from 5 cm to 15 cm is :

A spring of force constant 800 N/m has an extension of 5 cm . The work done in extending it from 5 cm to 15 cm is

A spring of force constant 800 Nm^(-1) is stretched initially by 5 cm . The work done in stretching from 5 cm to 15 cm is

A spring of spring constant 8 N/cm has an extension of 5 cm. The minimum work done in Joule in increasing the extension from 5 cm to 15 cm is

K is a force constant of a spring. The work done in increasing its extension from l_1 to l_2 will be