A mass of m = 0 . 5 kg is pulled along a surface using a spring balance. The spring balance is moved with a constant velocity of v = 0 . 1 m / s . The motion exhibits a clear stick – slip behaviour. The reading of the spring balance varies between 8 N and 1 4 N . The stiffness of the spring k = 1 N / mm . a ) Calculate the ratio between the static and dynamic coefficient of friction. b ) Calculate the fluctuation of stick – slip motion. c ) Calculate the frequency of motion. d ) Calculate the natural frequency of the mass spring system.a