In the previous type of block-on-plank motion, a block is initially at the left end of a plank of length L. Both start from rest and the constant relative acceleration of the plank with respect to the block is aᵣ. The time after which the block reaches the other end of the plank is:
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Question

In the previous type of block-on-plank motion, a block is initially at the left end of a plank of length L. Both start from rest and the constant relative acceleration of the plank with respect to the block is aᵣ. The time after which the block reaches the other end of the plank is:

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G1 Physics · Accepted Answer

Initially relative velocity is zero. Relative displacement needed is L. Therefore L = ½aᵣt². Hence t = √(2L/aᵣ).