A spring of force constant 800 N/m has an extension of 5 cm

• Work Energy

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

1. 32 J
2. 8 J
3. 24 J
4. 16 J

Solution

The work done is stored as Potential Eenergy in the spring. It is given by

W = ½ * k(x₂² - x₁²) 

x₁ = 5 cm

x₂ = 15 cm

Force constant, k = 800 N/m = 8 N/cm

W = ½ * 8(15² - 5²) = ½ * 8(225 - 25)

W = 800 N cm = 8 N m = 8 J

The correct option is B.