JEE Advanced 2020 Full Test 2 Paper 2

Figure shows a spring attached to a 2.0kg block. The other end of the spring is pulled by a motorized toy train that moves forward at constant speed 6.0cm∕s. The spring constant is 50N∕m and the coefficient of static friction between the block and the surface is 0.60. The spring is at its natural length at t=0s when the train starts to move. When does the block slip (express your answer in second )?