Question

A body of mass m= 1 kg is dropped from a height h= 40 cm on a horizontal platform fixed to one end of an elastic spring the other being fixed to a base as shown in fig. As a result the spring is compressed by an amount x = 10 cm. The force constant of the spring is

• A. 600 N/m
• B. 800 N/m
• C. 1000 N/m
• D. 1200 N/m

Answer 1

The correct option is B 800 N/m

$\begin{array}{c}\frac{-1}{2}K{x}^2=0-\frac{1}{2}m{v}^2\\ K.\frac{1}{100}=\mathrm{1.2.10.}\frac{4}{10}\\ K=800N/m\\ Hence,\\ optionBiscorrectanswer.\end{array}$