Give the example of variable force. Write the formula of Hook’s law.

A massless platform is kept on a light elastic spring as shown in fig. When a sand particle of mass $0.1\; kg$ is dropped on the pan from a height of $0.24 \;m$, the particle strikes the pan and spring is compressed by $0.01\; m$.

From what height should the particle be dropped to cause a compression of $0.04\; m$.

Explain the elastic potential energy of spring and obtain an expression for this energy.

In stretching a spring by $2\,cm$ energy stored is given by $U,$ then more stretching by $10\,cm$ energy stored will be

A spring of force constant $10\, N/m$ has an initial stretch $0.20\, m.$  In changing the stretch to $0.25\, m$, the increase in potential energy is about.....$joule$

A block of mass $\sqrt{2}\,kg$ is released from the top of an inclined smooth surface as shown in figure. If spring constant of spring is $100\,N / m$ and block comes to rest after compressing the spring by $1 \,m$, then the distance travelled by block before it comes to rest is ......... $m$