Calculating the torque in a moving arm of a catapult

[helloabhihere]

Find the ideal energy transferred to a projectile in a spring launching device, the device is a catapult which involves a bungee cord being stretched and has the cord attached to a throwarm which is pivoting on a circular rod. i have calculated the elastic energy stored in the cord at the maximum stretch and in order to calculate ideal energy, i need to find the energy required to get the throwarm moving so i can subtract the two to find the ideal energy that should be transferred to the projectile. My teacher says that you need to use torque and lever energy knowledge to solve this problem. (Sorry for the bad english)

my catapult looks something like this
http://www.stormthecastle.com/catapu...pult-index.htm
on the same page if you scroll down, it will show you how the catapult works i a video
please check out this link and the video as i need a bit of help calculating the torque

 

[jbsteele]

and lever energy required to get the throwarm moving. To calculate the ideal energy transferred to the projectile, you need to calculate the torque and lever energy required to get the throwarm moving. The torque is the force multiplied by the distance from the pivot point, and the lever energy is the force multiplied by the distance from the fulcrum. First, calculate the force of the bungee cord on the throwarm. This can be done by using Hooke's law, F = -kx, where F is the force, k is the spring constant of the bungee cord, and x is the maximum stretch of the bungee cord. Next, calculate the torque of the bungee cord on the throwarm. This can be done by multiplying the force calculated in the previous step by the distance from the pivot point. Finally, calculate the lever energy of the bungee cord on the throwarm. This can be done by multiplying the force calculated in the first step by the distance from the fulcrum. Once you have calculated the torque and lever energy needed to get the throwarm moving, subtract this amount from the elastic energy stored in the bungee cord at the maximum stretch to get the ideal energy transferred to the projectile.

 

[nlightner]

To calculate the torque in a moving arm of a catapult, you will need to use the equation Torque = Force x Distance. In this case, the force would be the tension in the bungee cord and the distance would be the length of the throwarm. This will give you the torque required to move the throwarm.

To find the ideal energy transferred to the projectile, you will need to consider the energy stored in the bungee cord and the energy required to move the throwarm. As you have already calculated the elastic energy stored in the cord at maximum stretch, you now need to calculate the energy required to move the throwarm. This can be done by considering the work done by the torque in rotating the throwarm. The equation for work is Work = Force x Distance, so you will need to multiply the torque by the angle through which the throwarm rotates.

Once you have calculated the energy required to move the throwarm, you can subtract it from the elastic energy stored in the cord to find the ideal energy that should be transferred to the projectile. This will give you an estimate of the maximum potential energy that can be transferred to the projectile in the catapult.

It is important to keep in mind that this is an ideal calculation and does not take into account any losses due to friction or other factors. However, using torque and lever energy knowledge, you can get a good estimate of the ideal energy transferred to the projectile in a catapult.