# Torque, lever and mass

The Force used in a catapult is exerted near its axis. If we double the length of the arm of the catapult, but still use the same Force at the same point as before near the same axis, does the distance in the Torque equation change?Edit (In an experiment we have found that the longer arm/lever makes the ball fly a longer distance, but how do we compute this into the equation?) Also, how can one combine the mass of the ball used by the catapult with the calculation of the torque?

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What type of catapult are you using? An onager/trebuchet/mangonel/etc? Also, most if not all types of catapults do not exert the force at the axis, it is exerted along the arm. – Jim Apr 23 '13 at 14:07
Hi, It is an onager catapult with both twisted rubber at the axis and a rubber band just above it, pushing the arm near its base like a slingshot. We added a couple of rubber bands at a time to measure the effect of force on the distance 3 types of balls with the same size but different mass achieved. Is the force element perpendicular to the arm not related to the exact spot (distance from axis) where the force is exerted? Thank you – user23513 Apr 23 '13 at 14:40
Any insights and/or recommendations on where to read relevant info will be highly appreciated! – user23513 Apr 25 '13 at 19:44