Candy catapult

At a child s fair, two booths present almost identical candy catapults. At both booths, candies are accelerated on a horizontal plane using rubber bands. At booth A, the rubber band is stressed for each shot by lengthening it from the initial length /a = by A a = const (figure 12.1(a)), whereas booth B stresses the rubber using a rope, a pulley, and a weight loading the band with a force Fb = const. 

The cross section of both rubber bands is identical (A). Assume that both rubber bands are linear-elastic. Young s modulus of the rubber band of booth B is twice as large as that at booth A Fb = 2Fa- 

At both booths, the take-off velocity of the candies is disappointingly small. We want to find a way to increase the velocity without using additional material or changing the construction of the catapults. 

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