A small rubber ball (weight W = 450 mN) is attached by a rubber cord to a wood paddle (see figure). The natural length of the cord is L0 = 200 mm, its crosssectional area is A = 1.6 mm2, and its modulus of elasticity is E = 2.0 MPa. After being struck by the paddle, the ball stretches the cord to a total length L1 = 900 mm.
What was the velocity v of the ball when it left the paddle? (Assume linearly elastic behavior of the rubber cord, and disregard the potential energy due to any change in elevation of the ball.)