Question

A plank 2.00 cm thick and 15.0 cm wide is firmly attached to the railing of a ship by clamps so that the rest of the board extends 2.00 m horizontally over the sea below. A man of mass 80.0 kg is forced to stand on the very end. IF the end of the board drops by 5.00cm because of the man's weight, find the shear modulus of the wood.

I'm not sure how you find the force in order to complete the shear modulus equation of F/A divided by Delta L/L